Showing papers in "Journal of The World Aquaculture Society in 2012"
TL;DR: This review focuses on the application of garlic in various fish diseases treatments and the prospects of using garlic preparations in aquaculture.
Abstract: The extensive use of antibiotics and various chemical compounds has resulted in drug residue and resistant pathogens in treated fish. Drug residue not only pollutes the environment, but also threatens human consumers. In contrast, garlic as a well-known natural antibiotic that causes no environmental or physical side effects has shown to be effective for the treatment of many diseases in humans and animals owing to its antimicrobial, antioxidant, and antihypertensive properties. In aquacultural operations, garlic with dose optimization is strongly recommended. This review focuses on the application of garlic in various fish diseases treatments and the prospects of using garlic preparations in aquaculture.
97 citations
TL;DR: Dietary inclusion of 0.5% OP was effective at improving lysozyme activity of fish, and OP seemed to be an effective immunostimulant to lower mortality upon E. tarda infection.
Abstract: This study tested the onion powder (OP) supplementation in the diet of the olive flounder on the growth, body composition, and lysozyme activity. Thirty-five fish averaging 5.1 g were randomly stocked into 18 individual 180-L flow-through tanks. A commercially available OP was used as a dietary additive. Six experimental diets were prepared to contain OP at the concentrations of 0, 0.5, 1, 2, 3, and 5% for diets OP-0, OP-0.5, OP-1, OP-2, OP-3, and OP-5, respectively. After the 8-wk feeding trial, 20 fish from each tank were infected with Edwardsiella tarda and mortality was monitored for the following 96 h. No distinctive improvement in survival, weight gain, or feed efficiency of fish was observed at the end of the 8-wk feeding trial. Lysozyme activity in fish fed the OP-0.5 diet was higher than that of fish fed the OP-0, OP-1, OP-2, OP-3, and OP-5 diets. The cumulative mortality of fish fed the OP-0.5, OP-1, OP-2, OP-3, and OP-5 diets was lower than that of fish fed the OP-0 diet at 72 h after E. tarda infection. Dietary inclusion of 0.5% OP was effective at improving lysozyme activity of fish, and OP seemed to be an effective immunostimulant to lower mortality upon E. tarda infection.
69 citations
TL;DR: The findings suggest that the salicylate method is a preferable alternative to the phenate methods for use in freshwater and saline water aquaculture applications.
Abstract: A study was conducted to compare the precision and accuracy of the phenate method and the salicylate method for determining total ammonia nitrogen concentration in water over a wide range of salinities. The two methods provided results that were highly correlated (P 0.05). In replicate analyses of the same samples, the salicylate method often gave a higher mean concentration of total ammonia nitrogen than was obtained with the phenate method. Also, precision was usually better for the salicylate method. Accuracy, as determined by spike recovery, was slightly superior for the salicylate method. The findings suggest that the salicylate method is a preferable alternative to the phenate methods for use in freshwater and saline water aquaculture applications.
68 citations
TL;DR: Natural products could be an important area of research because of the large diversity of compounds present in these products and the potential for anesthetic activity, increased safety, and low cost.
Abstract: Anesthetics can be used in fish culture to minimize stressful situations and facilitate handling (Coyle et al. 2004). However, certain anesthetics may promote a stress response in the animals (Zahl et al. 2010). Thus, it is important to search for new compounds with potential anesthetic activity, increased safety, and low cost. In this context, natural products could be an important area of research because of the large diversity of compounds present in these products (Keene et al. 1998; Goncalves et al. 2008; Cunha et al. 2010, 2011). The plants Aloysia gratissima (Gillies & Hook) Troncoso (Verbenaceae) and Ocimum gratissimum L. (Lamiaceae) have been used as sedatives in popular medicine (Di Stasi et al. 2002; Goleniowski et al. 2006). Essential oil (EO) rich in eugenol obtained from O. gratissimum has shown to be effective in mice as anticonvulsant and sedative (Freire
53 citations
TL;DR: Results showed that the algae increased in absorbency and dry biomass as salinity decreased, and the specific growth rate (SGR) of the algae decreased significantly when the salinity increased.
Abstract: Salinity fluctuation is an important factor affecting outdoor microalgae culture. This investigation examined the effect of salinity change (Tr-1:3515 g/L, Tr-2:3525 g/L, Tr-3:3535 g/L, Tr-4:3545 g/L, and Tr-5:3555 g/L) on growth and the biochemical composition of Nannochloropsis oculata, a candidate for biodiesel production in indoor photo-bioreactors. Results showed that the algae increased in absorbency and dry biomass as salinity decreased. When the salinity increased, the specific growth rate (SGR) of the algae decreased significantly. The salinity stress also affected the pigments of the algae, the chlorophyll-a, and carotenoid contents of the algae which decreased with the increase of salinity from 45 to 55 g/L. The fatty acid methyl esters (FAME) content (% of dry biomass) increased with the increase of salinity (e.g., Tr-4 and Tr-5). The algae was rich in C16:0 (palmitic acid), C16:1n-7 (palmitoleic acid), and C20:5n-3 (eicosapentaenoic acid), and C16:0 content increased with decreasing salinity from 35 to 15 g/L, but C16:1n-7 content was high in all the treatments ranging from 25.25 +/- 1.42% in Tr-1 to 27.05 +/- 1.13% in Tr-5.
51 citations
TL;DR: Growth rates and production efficiencies for the urchins in this study were higher than in previous feeding studies with adult Lytechinus variegatus, and weight gain varied directly and significantly with protein intake.
Abstract: In this study, we evaluated protein and carbohydrate levels in cold-extruded dry diets. Sea urchins (12.6 ± 0.12 SE g wet weight, 29.5 ± 0.11 SE mm diameter) were collected from St. Joseph Bay, Florida (30°N, 85.5°W), and transported to the Texas Agrilife Research Mariculture Laboratory in Port Aransas, Texas. Urchins were held individually in replicated enclosures within a recirculating seawater system (32 ± 2 ppt and 22 ± 2 C). Urchins (n = 16urchins) were fed diets that differed in protein : carbohydrate levels (31:33%, 25:39%, 21:44%, and 17:47% dry weight) for 12-wk. Survival was 100% in all diet treatments. Urchins fed the 31:33% protein : carbohydrate diet consumed less feed, more dry protein, less dry carbohydrate, less energy, and had lower feed conversion ratios than urchins fed other diets. Urchins fed the 31:33% protein : carbohydrate diet had larger test diameters, total wet weights, production efficiencies, and gonad production efficiencies than urchins in the other diets. Weight gain varied directly and significantly with protein intake. Sufficient energy was available for maximum weight gain as protein was spared. Growth rates and production efficiencies for the urchins in this study were higher than in previous feeding studies with adult Lytechinus variegatus.
46 citations
TL;DR: Results indicate that addition of 1% CA or AA, to a low-FM diet without inorganic P supplementation enhanced fish growth, P retention, and decreased P load to the environment.
Abstract: This study was conducted to evaluate the effect of citric acid (CA) and amino acid chelated trace elements (AA) on the growth, phosphorus (P) utilization efficiency and loading in rainbow trout fed a diet formulated with a low-fish meal (FM) concentration. A low-FM basal diet with or without monocalcium phosphate supplementation served as positive and negative control correspondingly. Dietary treatments consisted of the basal diet supplemented either with 1% CA, AA (equivalent to 40 Zn, 20 Mn, and 4 Cu mg/Kg of diet instead of inorganic trace element mix) or a combination of both. Duplicate groups of 35 fish (13.2 g) were fed until apparent satiation during 12 wk. Group of fish fed diets supplemented with 1% CA or AA had a final growth and feed utilization similar to that observed in fish fed the positive control diet (P > 0.05). P absorption was increased with the addition of CA or AA. P retention efficiency rates for these diets were higher in comparison with the rest of the treatments consequently showing the lowest P loading values (P < 0.05). The results indicate that addition of 1% CA or AA, to a low-FM diet without inorganic P supplementation enhanced fish growth, P retention, and decreased P load to the environment.
45 citations
TL;DR: It is concluded that salinity concentration of 2 ppt can be used for pacu larval rearing, allowing the Artemia nauplii lifetime to last longer and cause faster fish growth.
Abstract: The aim of this study was to evaluate the growth and survival of pacu, Piaractus mesopotamicus, larvae reared in different salinities and to determine the Artemia nauplii life span in freshwater and in saline water. First feeding 5-d-old pacu larvae were reared in freshwater or at 2, 4, 6, 8, 10, 12, and 14 ppt salinities. The larvae were reared in 1.5-L aquaria at a density of 10 larvae/L with three replicates per treatment. After 10 d of rearing, significant differences (P < 0.05) were observed for growth and survival. Larval growth was higher at 2 and 4 ppt, and survival at 2 ppt was 100%. In freshwater and at 4, 6 and 8 ppt, the survival was 91.1, 93.3, 73.3, and 39.9%, respectively. At higher salinities, there was 100% mortality after 2 h (12 and 14 ppt) and 8 h (10 ppt) of exposure. The slightly saline water of at least 2 ppt increased the Artemia nauplii life span compared to the life span in freshwater. Later, in a second trial, 5-d-old pacu larvae were reared in freshwater and at 2 and 4 ppt salinities during the first 5 or 10 d of active feeding, and then the fish were transferred to freshwater. At the end of 15 d, larval growth was lower in freshwater (42 mg) than in treatments 2 and 4 ppt (59–63 mg). The abrupt transfer of fish from freshwater to slightly saline water and the return to freshwater did not affect the survival rates (89–97%). The larvae were able to adapt to these saline environments and handle abrupt changes in salt concentration. We concluded that salinity concentration of 2 ppt can be used for pacu larval rearing, allowing the Artemia nauplii lifetime to last longer and cause faster fish growth.
40 citations
TL;DR: The scale-up of spotted rose snapper larval rearing is described and the percentage of viable larvae at 48 h after hatching was 79.7 ± 1.9%.
Abstract: The scale-up of spotted rose snapper, Lutjanus guttatus, larval rearing is described. Fertilized eggs (480,000) were obtained from a 1-d harvest of a natural spawning captive broodstock acclimatized for 1 yr and 6 mo in two fiberglass tanks (18 m3). Fourteen hours after spawning, 89.6% of the collected eggs were floating, of which 96.2% were transparent with live embryos. Incubation at 25–26 C lasted 21 h, with 90.2 ± 2.1% hatching percentage of normal larvae. The percentage of viable larvae at 48 h after hatching was 79.7 ± 1.9%. Initial stocking density was 10.4 ± 1.0 larvae/L 2 days after hatching (d.p.h.). A total of 22,600 juveniles (1256 ± 170 juveniles/m3) were harvested from six 3-m3 cylindrical fiberglass tanks. Average survival was 12.1 ± 1.1%. Final mean length and weight were 5.5 ± 0.05 cm and 2.24 ± 0.04 g, respectively. Growth expressed in total length was TL = 2.1476e0.0543t (R2 = 0.9911). Final mean biomass and condition factor were 2.8 kg/m3, 12.3% and 1.346. General length-weight ratio was W = 0.05460 LT2.2306.
40 citations
TL;DR: Most of the prepared feeds outperformed kelp, and significant differences in growth were detected between some of the diets, but further diet refinement and/or use of finishing diets may be necessary to optimize gonad quality.
Abstract: The effects of varying protein and carbohydrate levels in prepared diets on the somatic growth of juvenile green sea urchins, Strongylocentrotus droebachiensis, were examined Ten diets were tested on 600 hatchery reared urchins (mean start weight = 011 g) for 6 mo with three replicate groups per diet Nine of the diets were prepared specifically for urchins and varied in protein (16–40% protein) and carbohydrate (29–49% carbohydrate) levels The other two diets consisted of a commercially available abalone diet and the kelp, Saccharina latissima Weight measurements were carried out at 6-wk intervals, and at the end of the study urchins were individually weighed and a subsample from each treatment was analyzed for gonad weight and color End weights after 6 mo ranged from 256 g for urchins fed the abalone diet to 611 g for urchins fed one of the prepared diets Most of the prepared feeds outperformed kelp, and significant differences in growth were detected between some of the diets In general, diets with lower protein levels (16–22% protein) and higher carbohydrate levels (>40% carbohydrate) produced the fastest growth However, further diet refinement and/or use of finishing diets may be necessary to optimize gonad quality
40 citations
TL;DR: RPC did not show detrimental effects on the intestinal morphology and modification of tissue enzyme activity in rainbow trout and Liver samples of fish fed with RPC-based diets were characterized by a slight decrease in lipid vacuolizations and a decreasing trend in the Ceroid Substances Presence Index.
Abstract: This study was carried out in order to investigate the histological and biochemical responses in the gastrointestinal tract (GIT) of rainbow trout fed a rice protein concentrate (RPC). A stock of 360 juvenile rainbow trout (62.4 ± 0.3 g) were randomly distributed into 12 fiberglass tanks and fed with four experimental diets obtained by including graded levels of RPC (RPC: 0, 20, 35, and 53%) replacing fish meal on dry weight basis. The experimental plan was balanced and monofactorial, with four treatments and three replicates. At the end of the experiment, 15 fish per treatment were killed, and different tissues were sampled for biochemical and histological analyses. The results showed that total alkaline proteases were unaffected by RPC inclusion level. Amylase and lipase activities showed slight differences between the groups for all examined tracts. No histopathological changes were observed in GIT for any of the dietary treatments. Liver samples of fish fed with RPC-based diets were characterized by a slight decrease in lipid vacuolizations and a decreasing trend in the Ceroid Substances Presence Index. In conclusion, RPC did not show detrimental effects on the intestinal morphology and modification of tissue enzyme activity in rainbow trout.
TL;DR: The overall results in this study suggested that the higher 34% protein was superior for juvenile grass carp and an increase in dietary starch level did not improve growth or protein utilization but enhanced whole-body lipid deposition and liver, viscera and muscle lipid level.
Abstract: Six practical extruded diets were formulated to investigate the effect of graded levels of starch (17, 22, and 26%) associated with either 30 or 34% protein level on growth, feed utilization, body composition, and hepatic transaminases of juvenile grass carp, Ctenopharyngodon idella. Over an 8-wk growth trial, survival rates (99–100%) were not significantly affected (P > 0.05) by dietary treatments. Independent of dietary starch level, weight gain (WG, %), specific growth rate (SGR, %/d), and feed efficiency ratio (FER) showed significant better response (P < 0.05) of fish fed 34% protein diet than those of fish fed 30% protein diet. Protein productive value (PPV) was only affected by dietary protein level, with higher values in the 34% protein level than their 30% counterparts. Irrespective of dietary protein level, lipid productive value (LPV), energy productive value (EPV), viscerosomatic index (VSI, %), intraperitoneal fat ratio (IPF, %), and whole body, liver, and muscle lipid level increased with increasing starch supply. At the same protein level, plasma triacylglycerol (TG), cholesterol (CHO), and low density lipoprotein-cholesterol (LDL-C) increased when dietary starch level increased from 17 to 26%. Neither dietary protein level nor starch level affected activities of hepatic alanine aminotransferase (ALAT) and aspartate transferase (ASAT). The overall results in this study suggested that the higher 34% protein was superior for juvenile grass carp and an increase in dietary starch level did not improve growth or protein utilization but enhanced whole-body lipid deposition and liver, viscera and muscle lipid level. The diet containing 34% protein and 17% starch was optimal for practical production of juvenile grass carp.
TL;DR: Results show that hybrid catfish can utilize CGF at levels up to 30% of the diet (10% CSM), and a combination of CGF and CSM up to 25% each without significantly affecting growth, diet consumption, FCR, and fillet proximate nutrient composition.
Abstract: This study examined the use of corn gluten feed (CGF) and cottonseed meal (CSM) to partially replace soybean meal and corn in diets for pond-raised hybrid catfish, Ictalurus punctatus×I. furcatus. Five 28% protein diets containing various combinations of CGF and CSM were evaluated. Fingerling hybrid catfish (mean initial weight: 45 g/fish) were stocked into 25, 0.04-ha ponds at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation for a 179-d growing season. CGF at 30% of the diet (10% CSM) and a combination of CGF and CSM up to 25% each did not affect physical quality (percentages floatability and feed dust) of the diet. No significant differences were observed in total amount of diet fed, net yield, diet consumption, weight gain, feed conversion ratio (FCR), survival, and fillet proximate nutrient composition among fish fed various diets. Results show that hybrid catfish can utilize CGF at levels up to 30% of the diet (10% CSM), and a combination of CGF and CSM up to 25% each without significantly affecting growth, diet consumption, FCR, and fillet proximate nutrient composition. However, a combination of CGF and CSM at 20% each and above reduced carcass yield.
TL;DR: The polymerase chain reaction analysis confirmed the concentration-dependent variation in WSSV infection.
Abstract: This study was carried out to determine the effect of seaweed polysaccharide, fucoidan from brown seaweed, Sargassum wightii, on Penaeus monodon postlarvae (PL) against white spot syndrome virus (WSSV). The fucoidan was extracted from S. wightii, and the yield was observed as 2.832 ± 0.204%. Artemia franciscana nauplii were enriched with extracted fucoidan at four different concentrations (100, 200, 300, and 400 mg/L) and fed to shrimp P. monodon PL for 20 d. After feeding experiment, the P. monodon PL were challenged with WSSV, and the mortality percentage was recorded daily up to 21 d. During the challenge test, the control PL showed 100% cumulative mortality within 9 d, but the fucoidan-enriched Artemia nauplii fed groups of PL exhibited 60–94% cumulative mortality within 21 d. The reduction in mortality percentage of experimental groups of PL over control PL was ranged between 33.71 and 61.65%. The polymerase chain reaction analysis confirmed the concentration-dependent variation in WSSV infection.
TL;DR: This study was conducted to quantify dietary vitamin C requirement of fingerling, Cirrhinus mrigal by feeding casein-gelatin based purified diets containing nine levels of vitamin C as l-ascorbyl-2-polyphosphate to triplicate groups of fish to apparent satiation for 16 wk.
Abstract: This study was conducted to quantify dietary vitamin C requirement of fingerling, Cirrhinus mrigala, (0.79 ± 0.07 g; 3.51 ± 0.15 cm) by feeding casein-gelatin based purified diets (400 g/kg crude protein; 3.45 kcal/g digestible energy) containing nine levels of vitamin C as l-ascorbyl-2-polyphosphate (0.0, 5, 15, 25, 35, 45, 55, 75, and 95 mg vitamin C equivalent/kg diet) to triplicate groups of fish to apparent satiation for 16 wk. Absolute weight gain (AWG, g/fish), feed conversion ratio (FCR), protein retention efficiency (PRE%), RNA/DNA ratio, hemoglobin (Hb, g/dL), and hematocrit value (Hct%) were taken as the response criteria to determine vitamin C requirement of mrigal. Fish fed diet with 35 mg/kg vitamin C had significantly higher AWG (9.94 g/fish), FCR (1.39), PRE (27.72%), RNA/DNA ratio (4.18), Hb (11.15 g/dL), and Hct (34.44%) values. However, liver vitamin C concentration was found to be higher (64.92 µg/g wet tissue) in diet containing 45 mg vitamin C/kg. Broken-line regression analysis of AWG data estimated the requirement of 35.65 mg/kg, whereas that of the liver vitamin C concentration data projected the requirement to 41.99 mg/kg.
TL;DR: There is increasing interest in intensive production of Ictalurid catfish in the United States and a better understanding of water quality dynamics in intensive culture is needed, and budgets for water, nitrogen, and phosphorus were estimated over a production season.
Abstract: There is increasing interest in intensive production of Ictalurid catfish in the United States and a better understanding of water quality dynamics in intensive culture is needed. Budgets for water, nitrogen, and phosphorus were estimated over a production season (March–November) for an In-pond Raceway System for channel catfish, Ictalurus punctatus, and hybrid catfish, I. punctatus × I. furcatus, with co-culture of paddlefish, Polyodon spathula, and Nile tilapia, Oreochromis niloticus. In addition to the rainfall and runoff, 70 cm of water was applied from a well to offset evaporation and seepage. Production of each kilogram of live catfish required 1.50 kg of feed and released 51.7 g nitrogen and 9.7 g phosphorus. Harvest of catfish accounted for 34.0% of nitrogen and 37.1% of phosphorus applied in feed. Seepage and overflow removed only small portions of nitrogen and phosphorus, while denitrification and ammonia volatilization removed large amounts of nitrogen. Some nitrogen accumulated in sediment. Phosphorus was harvested in fish and absorbed by pond sediment. Mechanical aeration aided in maintaining appropriate dissolved oxygen levels for fish production.
TL;DR: Dietary canola meal supplementation showed significant effect on hepatic composition of tilapia, but not muscle composition, suggesting that dietary fish meal replacement by canola Meal had significant effects on nutrient metabolism in the liver.
Abstract: An 8-wk feeding trial was conducted to evaluate the potential of replacing fish meal with canola meal in experimental diets for genetically improved farmed tilapia (GIFT) strain of Nile tilapia, Oreochromis niloticus (mean initial weight: 20.0 ± 0.62 g, means ± SD), reared in fresh water. Six isonitrogenous (30% crude protein) and isolipidic (10%) diets were formulated with canola meal included at six levels of 0 (control), 11, 22, 33, 44, and 55%, replacing 0, 15, 30, 45, 60, and 75% fish meal, respectively. Growth performance and feed utilization showed no significant differences among the treatments. In general, dietary canola meal supplementation showed significant effect on hepatic composition of tilapia, but not muscle composition. Viscerosomatic index tended to increase with increasing dietary canola meal levels from 0 to 44%, and then declined when dietary canola meal levels further increased from 44 to 55%. Dietary fish meal replacement by canola meal significantly influenced several hepatic enzymatic activities, including succinate dehydrogenase, lactate dehydrogenase, malic dehydrogenase, lipoprotein lipase, and hepatic lipase, suggesting that dietary fish meal replacement by canola meal had significant effects on nutrient metabolism in the liver. Based on the information above, 75% of dietary fish meal could be replaced by canola meal with no effect on growth performance of GIFT strain of Nile tilapia. Use of canola meal in practical diets for GIFT stain of Nile tilapia may allow producers and feed mills to formulate more economical diets.
TL;DR: Findings indicate that certain issues need to be addressed regarding adequate description of analytical methods followed for FA analysis, presentation and interpretation of FA results and may help to highlight critical points that should be considered from the researchers' and scientific journals' sides in order to foster more informative research publications.
Abstract: The present literature overview was carried out in order to assess the use of fatty acids (FA) analysis in fish farming research during the last decade. As aquaculture products are mainly intended for human consumption, the overview is focused on fish fillet, carcass or whole body FA, as a major aspect of fish nutritional value. This survey used 394 papers and demonstrated that a) 71% of papers report FA as relative percentage of total FA (% totFA), b) 23% of papers report actual FA amounts, c) in 63% of papers not enough information is provided in âMaterials and Methodsâ section to understand exactly how FA analysis was performed, and d) based on FA percentages, results are not always the same as when based on FA amounts, and thus divergent conclusions about treatment effects could be drawn. These findings indicate that certain issues need to be addressed regarding adequate description of analytical methods followed for FA analysis, presentation and interpretation of FA results and may help to highlight critical points that should be considered from the researchers' and scientific journals' sides in order to foster more informative research publications.
TL;DR: In penaeid larvae, nematodes turned out to be a good live food that can compete with conventional feeding methods even though there is still room for improvements.
Abstract: Live feeds are essential in larval nutrition of many fish and crustacean species. As the consumers' demand for aquaculture products is growing rapidly, the demand for live feeds in larviculture is increasing as well. To satisfy the growing demand, research has taken steps to develop new innovative live feeds. Several studies focused on nematodes as a potential food source for larvae. Production methods, culture media, harvest, and enrichment procedures for nematodes presented in these studies are reviewed here. Many studies fed nematodes to different species of fish and crustaceans to test applicability in larval nutrition. The results of these feeding trials in terms of larval performance as well as ingestion and digestion of nematodes in the larvae's gut are reviewed here as well. In addition, a summary of advantages and disadvantages of nematodes as live food and an outlook on future challenges of production and application of nematodes in larviculture are also presented.
In summary, several different production methods including innovative culture media for nematodes have been developed. The species Panagrellus redivivus has been used in most of the reviewed studies. It reproduces extremely fast and can be cultivated by very simple means of production. Other species such as Turbatrix aceti and Caenorhabditis elegans have been tested in a few studies as well. However, a complete production cycle for mass production appropriate for use in aquaculture has not been developed yet for any of these species. Enrichment trials for amino acids revealed only a very limited potential to manipulate amino acid profiles in nematodes. In contrast, fatty acid composition turned out to be quite variable depending on the culture media used for nematode production. By adding oils containing large quantities of essential fatty acids to the culture media, these fatty acids could be enriched in nematodes and provided to larvae. This allows tailoring fatty acid composition according to the needs of the respective larvae. It could be shown that nematodes can be digested by fish larvae even though they possess a robust cuticle. Larval performance depends strongly on the respective species of fish to which the nematodes are fed. Nematodes seemed to work particularly well for crustacean larvae. In penaeid larvae, nematodes turned out to be a good live food that can compete with conventional feeding methods even though there is still room for improvements. For future use in larviculture, appropriate methods for mass production, harvest, and feeding need to be developed. Additionally, more data on optimized feeding levels for different fish and crustacean species will be required.
TL;DR: The effect of mysids to enhance reproduction efficiency in H. hippocampus is shown for the first time, as well as the effect of Artemia on the spawning quality of Hippocampus hippocampus.
Abstract: The importance of a suitable diet for reproduction has been recognized as one of the major factors in ornamental aquaculture. In seahorses, mysids have been described as preys in the wild. Also, Artemia has been usually employed for rearing fish, including syngnathids. Therefore, the aim of this work was to evaluate the effect of these live preys on the spawning quality of Hippocampus hippocampus. After 108 d, no differences were found in adults concerning all biological parameters evaluated, but broodstock fed on mysids showed better results than Artemia regarding number of spawning events (12 vs. 3), brood sizes (233.50 ± 59.04 vs. 68.00 ± 57.97 juveniles), and newborn seahorses standard length (10.61 ± 0.64 vs. 8.75 ± 1.32 mm). The better nutritional quality of mysids, overall in Docosahexanoic acid, could be one of the main responsible factors. However, mysids stock is conditioned by natural catches and rearing techniques are little known. Another alternative would be to combine them with Artemia in mixed diet. Further research must be done concerning mysids breeding techniques to delineate their employment as a sustainable prey for seahorse aquaculture. This trial showed for the first time the effect of mysids to enhance reproduction efficiency in H. hippocampus.
TL;DR: In this study, the volatility in variable production costs and nominal sales price, and distribution of cormorants on pond types and regionally were key factors in resulting economic loss estimates.
Abstract: The Yazoo River Basin of Mississippi, USA, supports the largest concentration of hectares devoted to channel catfish, Ictalurus punctatus, aquaculture production in North America. The Yazoo Basin also supports large numbers of resident, wintering and migrating fish-eating birds, with the Double-crested Cormorant, Phalacrocorax auritus, implicated as the most serious depredating species. We used data from aerial surveys of numbers and distribution of cormorants in the Yazoo Basin and on commercial catfish ponds during winters (November–April) 2000–2001 and 2003–2004 to refine estimates of regional economic losses due to cormorant depredation. In both periods, the greatest monthly estimates of cormorant foraging occurred from 1 January to 31 March. Losses in terms of biomass, number, and dollar value were greater for foodfish ponds than fingerling ponds. Monthly weighted estimates of catfish consumed were 1775.3 and 1346.6 m.t. over winters 2000–2001 and 2003–2004, respectively. Total estimated losses for foodfish and fingerling ponds in 2000–2001 were $11.56 and $0.48 million, respectively, and in 2003–2004 were $5.22 and $0.40 million, respectively. Maximum dollar loss occurred during March in 2000–2001 and during February in 2003–2004. In this study, the volatility in variable production costs and nominal sales price, and distribution of cormorants on pond types and regionally were key factors in resulting economic loss estimates.
TL;DR: An organic diet which replaces FM with a combination of SBM and YE with added methionine and lysine is commercially feasible and further investigation into the increased use of these two ingredients as protein sources in aquaculture diets is warranted.
Abstract: Quantities of fish meal (FM) have remained level for the past several decades; however, demand has dramatically increased because of its inclusion in all animal production as a high-quality protein source. Soybean meal (SBM) is the most widely used plant-protein ingredient for replacing various proportions of FM in aquatic animal diets. However, use of SBM as the sole protein source has often resulted in reduced fish growth. There is a growing segment of consumers who desire organically grown seafood, and tilapia is one of the most-cultured fish in the world. As tilapia have herbivorous/omnivorous feeding habits, tilapia fed organic diets may allow producers to enter this rapidly developing market. A feeding experiment was conducted to evaluate the combination of organic SBM and an organic yeast extract (YE) as complete replacements for FM in Nile tilapia, Oreochromis niloticus, fry diets. Nine diets were formulated to contain various percentages of organic YE (0, 15, 30, and 45%) in combination with organic SBM (84–34%) with and without amino acid (methionine and lysine) supplementation.
At the conclusion of the study, fry fed a control diet containing 20% FM and fry fed a diet containing 45% YE/36%SBM with amino acid supplementation showed no significant differences (P > 0.05) in final weight, weight gain, and specific growth rate (SGR) compared to those fed all other diets. On the basis of these data, an organic diet which replaces FM with a combination of SBM and YE with added methionine and lysine is commercially feasible and further investigation into the increased use of these two ingredients as protein sources in aquaculture diets is warranted.
TL;DR: The results show that repeated low-intensity handling on gilthead sea bream alter the oxidative status of tissues such as liver, digestive tract, and muscle in the last term can affect its welfare and the concentration of MDA can be a good candidate as a biomarker of stress and welfare in fish.
Abstract: In this study, we investigated the effect of repeated handling on the oxidative state of gilthead sea bream, Sparus aurata. We determined the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione transferase (GST), and DT-diaphorase (DTD) in liver, digestive tract, brain, gills, and white muscle. We also measured the lipid-peroxidation level (malondialdehyde – MDA – concentration) and the glucose 6-phosphate dehydrogenase activity (G6PDH). The results show that repeated low-intensity handling on gilthead sea bream alter the oxidative status of tissues such as liver, digestive tract, and muscle in the last term can affect its welfare. The brain in a situation of handling stress is protected from oxidative damage by the activity of antioxidant enzymes. Finally, the concentration of MDA in tissues can be a good candidate as a biomarker of stress and welfare in fish.
TL;DR: The formulated diet achieved better growth of abalone than the dry sea tangle regardless of temperature and 20 C seemed to be recommendable for abalone among temperature tested.
Abstract: Effects of feed type and temperature on growth and body composition of juvenile abalone, Haliotis discus hannai Ino, were determined. A 2 (feed types: formulated diet and dry sea tangle) × 3 (temperature conditions: 20, 23 and 26 C) factorial design with triplicate was used. Seventy juvenile abalone averaging 4.7 g were randomly distributed into each of 18, 50-L plastic rectangular containers. Six containers were placed into each temperature condition of three 1.3 ton concrete flow-through raceway systems. Abalone were daily fed with either the formulated diet or dry sea tangle once a day to satiation level. Survival was affected by feed type, but not by temperature. Weight gain of abalone was affected by both feed type and temperature. Regardless of temperature, weight gain of abalone fed the formulated diet was better than that of abalone fed the dry sea tangle. Shell length and width were affected by feed type, but not by temperature. In conclusion, weight gain of abalone was affected by both feed type and temperature, but feed type had a stronger effect than temperature. The formulated diet achieved better growth of abalone than the dry sea tangle regardless of temperature and 20 C seemed to be recommendable for abalone among temperature tested.
TL;DR: Increased species richness and Shannon index were observed in the foregut, midgut and hindgut samples in the probiotic group compared with the control group, which suggested that probiotic L. lactis MM1 could improve the autochthonous microbial diversity along the GI tract of E. coioides.
Abstract: The effect of dietary administration of probiotic Lactococcus lactis MM1 for 60 d on the autochthonous microbiota in the foregut, midgut and hindgut of juvenile grouper, Epinephelus coioides, was evaluated using polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE). Samples collected from the probiotic and control groups showed different DGGE patterns, while 11 common bands presented in both groups. The similarity dendrogram revealed three different clusters depending on the three sections of the gastrointestinal (GI) tract, and the probiotic triplicates in each GI section were generally clustered into one group distinctly different from the corresponding control triplicates. Increased species richness and Shannon index were observed in the foregut, midgut, and hindgut samples in the probiotic group compared with the control group, which suggested that probiotic L. lactis MM1 could improve the autochthonous microbial diversity along the GI tract of E. coioides. The growth of many potentially beneficial and unidentified bacteria was stimulated by the probiotic, whereas the growth of some potential harmful species, like Staphylococcus saprophyticus, was depressed.
TL;DR: Weaning using enriched Artemia as an intermediate step is confirmed as the most adequate strategy for red porgy larvae, and Digestive enzymes and selected fatty acids correlated well with performance responses to dietary regimes, thereby supporting the use of these parameters as sensitive and reliable indicators ofred porgy nutritional or physiological status during larval stages.
Abstract: Red porgy, Pagrus pagrus, is a candidate species for aquaculture diversification. The aim of this work was to assess whether an early supply of enriched Artemia (D1) or a direct step to dry diets (D3) would be advantageous weaning strategies for red porgy larvae, compared to a later supply of Artemia followed by dry diets (D2). Direct weaning to dry diet resulted in significantly lower growth, survival, pancreatic (trypsin and lipase), and intestinal (alkaline phosphatase) enzyme-specific activity, with the exception of leucine-alanine peptidase. The direct weaning strategy presented severe nutritional restrictions from early weaning stages with an associated delay of the maturation of digestive system. The two-step strategy presented in D1 and D2 resulted in comparable results in most parameters, including survival. Weaning using enriched Artemia as an intermediate step is confirmed as the most adequate strategy for red porgy larvae. Digestive enzymes and selected fatty acids correlated well with performance responses to dietary regimes, thereby supporting the use of these parameters as sensitive and reliable indicators of red porgy nutritional or physiological status during larval stages.
TL;DR: A reduction in potential environmentally harmful factors such as salinization, land requirements, greenhouse gas emissions, as well as transportation costs are achieved, making the UASB reactor an attractive possible alternative for saline aquaculture sludge management.
Abstract: Environmental pressure, land utilization, and economic feasibility have resulted in the development of recirculating aquaculture systems (RAS). For many RAS, sludge is collected and washed from the system to waste stabilization ponds (WSPs). However, disposal of brackishwater aquaculture sludge into WSP is often prohibited because the high salinity can interfere with treatment. Moreover, there are problems associated with WSPs because of elevated salt content, such as the common practice of reusing treated water and land application of stabilized sludge. We tested and compared the treatment of brackishwater aquaculture sludge in an upflow anaerobic sludge blanket (UASB) reactor as an alternative to a WSP. In UASB, wastewater flows upward through a blanket of granular sludge and is treated by anaerobic micro-organisms. Reduction in organic matter and 5-d biochemical oxygen demand by 97 and 91%, respectively, was achieved in a UASB as compared to corresponding reductions of 22 and 41% in a WSP. During the UASB digestion process, methane is produced and recovered. Overall, a reduction in potential environmentally harmful factors such as salinization, land requirements, greenhouse gas emissions, as well as transportation costs are achieved, making the UASB reactor an attractive possible alternative for saline aquaculture sludge management.
TL;DR: Performance in shell length is improved by 3.55% in the upward-selected line after one generation, indicating that mass selection for shell length in a base population of the Manila clam, R. philippinarum, is effective and encouraging.
Abstract: To determine whether genetic improvement could be attained through a selective breeding programme, divergent selection for shell length was conducted in a base population of the Manila clam, Ruditapes philippinarum. The 10% largest and 10% smallest clams were selected as parents for the upward-selected and downward-selected lines, respectively. Equal numbers of clams were randomly chosen to serve as parents for the control line before the selection. The selected and control lines were reared under the same environmental conditions at larvae, juvenile, and grow-out stages. The values of standardized responses to selection (SR) and realized heritability ( at the age of 360 d were 0.268 and 0.165 for the upward-selected line and 0.341 and 0.260 for the downward-selected line, respectively. Asymmetric differences were evident between the upward-selected and downward-selected lines in both SR and . Performance in shell length is improved by 3.55% in the upward-selected line after one generation, indicating that mass selection for shell length in a base population of the Manila clam, R. philippinarum, is effective and encouraging.
TL;DR: The observed changes in microbial community characteristics corresponded with, and may help to explain, significantly improved shrimp feed conversion ratios, growth rate, final weight, and biomass yield in the tanks with biofloc reduction.
Abstract: The microbial community in minimal-exchange, superintensive culture systems should be managed to cycle nutrients and enhance production. This paper explores the effects of biofloc concentration reduction and a fish-free diet on several microbial community characteristics. In 16, 3.5-m diameter, 71-cm deep outdoor tanks, shrimp were stocked at 460/m3. Eight of the tanks received a fish-free, plant-based feed and eight received a conventional feed containing fishmeal and fish oil. Within each diet type, biofloc concentration was reduced in four of the tanks and was not reduced in the other four tanks. Photosynthetically active radiation (PAR) extinction coefficients, photosynthetic oxygen production, chlorophyll-a (chl-a) concentrations, pheophytin-a (pheo-a) concentrations, and the sum of odd and branched chain fatty acid concentrations as a bacterial abundance indicator (BAI) were measured. Biofloc reduction significantly (P≤ 0.003) decreased PAR extinction coefficients, chl-a concentration, pheo-a concentration, and BAI concentration, while significantly increasing photosynthetic oxygen production. Diet did not significantly affect (P > 0.05) any of these measured parameters. The observed changes in microbial community characteristics corresponded with, and may help to explain, significantly improved shrimp feed conversion ratios, growth rate, final weight, and biomass yield in the tanks with biofloc reduction.
TL;DR: The results of two feeding trials showed both dl-Met and Met-Met can be equally utilized by red sea bream larvae and juveniles, and the development of digestive protease activity of larvae was significantly influenced by coating the amino acid, but the type of methionine was not a factor in changing the proteaseActivity of larvae.
Abstract: Growth trials for larvae and juvenile red sea bream, Pagrus major, were conducted to elucidate the efficacy of two molecular forms of methionine; dl-methionine (dl-Met) and methionine dipeptide (Met-Met). For the larvae experiment, five experimental diets were formulated and fed to fish (42 mg) for 30 days. A diet which has 15% soy protein isolate served as the control diet. Similarly, test diets supplemented with dl-Met and Met-Met at 0.5%, which were either precoated by zein or intact, were also formulated. For the juvenile experiment, five experimental diets were formulated wherein the control diet contained 25% soy protein isolate. Test diets were supplemented with dl-Met and Met-Met at 0.75%, which were either coated by carboxymethycellulose or intact and fed to juveniles (0.75 g) for 56 days. The results of two feeding trials showed both dl-Met and Met-Met can be equally utilized by red sea bream larvae and juveniles. Coating the amino acid significantly improved both fish larval and juvenile growth performance. The development of digestive protease activity of larvae was significantly influenced by coating the amino acid, but the type of methionine was not a factor in changing the protease activity of larvae.