Showing papers on "Polyculture published in 2010"

Shrimp polyculture: a potentially profitable, sustainable, but uncommon aquacultural practice

Abstract: Shrimp polyculture is not yet a common practice among farmers; however, this activity represents an important alternative to solving and ⁄or minimizing some of the problems that shrimp aquaculture has faced in the past two decades (environmental pollution, diseases and decreasing prices). In this context, many benefits have been achieved with some polyculture practices. Several species from diverse trophic levels have the potential to be co-cultured with shrimps. A good knowledge of the species that are candidates for polyculture and an adequately designed culture system are the most important points to consider when co-culturing shrimp with other species. The present paper is a review of the past, present and future of shrimp polyculture with other organisms.

A novel method for rearing first-feeding larval zebrafish: polyculture with Type L saltwater rotifers (Brachionus plicatilis).

Abstract: Promoting high rates of growth and survival can be a major challenge in zebrafish culture, especially during the first-feeding stage. Here we describe a new rearing technique in which zebrafish larvae are polycultured in static tanks with Type “L” saltwater rotifers (Brachionus plicatilis) for the first 5 days of feeding (days 5–9 postfertilization). To demonstrate the effectiveness of this technique, we conducted rearing trials using fish from two different strains: AB and nacre. Growth, survival, water quality, and rotifer density were assayed daily through the polyculture phase (days 5–9), and during the transition to standard rearing conditions (days 10–12). After that point, once the fish were fully integrated onto recirculating systems, parameters were measured once per week out to day 30. In all trials, the fish displayed high rates of growth and survival throughout the three phases (polyculture, transition, and recirculating flow), indicating that this method may be employed during the cr...

Water Quality, Fish Production and Economics of Nile Tilapia, Oreochromis niloticus, and African Catfish, Clarias gariepinus, Monoculture and Polycultures

Abstract: Twelve 400 m2 earthen ponds were used to test the effect of Nile tilapia, Oreochromis niloticus, African catfish, Clarius gariepinus, monoculture and polyculture on water quality, fish production and economic performance across a range of stocking ratios: 100% tilapia + 0% catfish, 75% tilapia + 25% catfish, 50% tilapia + 50% catfish, and 0% tilapia +100% catfish. All ponds were stocked at the rate of 3 fish/m2. Two-way ANOVA showed that culture period explained more than 60% of variation in water quality variables while treatment was responsible only for about 11%. Net fish yields were 5.71, 9.84, 11.03, and 11.35 tones/ha corresponding with daily weight gains of 36.60, 63.08, 70.69, and 72.75 kg/ha/d in the 0% catfish, 25% catfish, 50% catfish, and 100% catfish treatments, respectively. Feed consumed was 7.59, 10.84, 13.48, and 17.03 tones/ha for the four treatments, respectively. Fish yield and feed consumption were highest in the catfish monoculture (P < 0.05) followed by the 50% catfish, 25% catfish, and 0% catfish treatments. Net profit for both polyculture treatments was significantly higher than both monoculture treatments, although no significant differences were observed among polyculture or between the two monoculture treatments. The 25% catfish polyculture treatment generated the highest economic returns.

Use of Duckweed as Feed for Fishes in Polyculture

Abstract: Effect of duckweed supplementation as fish feed to polyculture system was investigated. Fish were reared for 90 days with or without duckweed supplementation. The ponds were fertilized with cowdung, urea and triple super phosphate. All the important physico-chemical factors including temperature, transparency, dissolved oxygen, total alkalinity, phosphate-phosphorus and nitrate-nitrogen were within productive ranges for fish culture. Ponds were stocked with silver carp, Thai sharputui, tilapia, common carp and mrigel. After a 90 days rearing period, net fish production was found to be significantly higher in fish fed duckweed at a rate of 20% of body weight compared to fish without duckweed supplement. It was concluded that duckweed can effectively be used as feed for polyculture of fish. Key words: Duckweed; polyculture; feed. DOI: 10.3329/jard.v7i1.4437 J Agric Rural Dev 7 (1&2), 157-160, June 2009

Carp polyculture in Central and Eastern Europe, the Caucasus and Central Asia

Abstract: This technical paper is a basic guide to carp pond polyculture practicable in the Central and Eastern Europe (CEE) and the Caucasus and Central Asia (CCA) countries. It provides an overview on the guiding principles, aspects and tasks, and presents the most applicable production techniques and patterns of carp polyculture. For further reading and more in-depth information on the suggested techniques and technologies, it also includes a list of relevant FAO publications. It is expected that this publication will help identify resources and contribute to the successful planning and realization of fish production by those fish pond owners and operators who need to strengthen and improve their knowledge on the subject. Woynarovich, A.; Moth-Poulsen, T.; Péteri, A. Carp polyculture in Central and Eastern Europe, the Caucasus and Central Asia: a manual. FAO Fisheries and Aquaculture Technical Paper. No. 554. Rome, FAO. 2010. 73p. TP554 carp_24_11_10.indd Sec2:iv 24/11/2010 10:58:56

Effect of high phosphate fertilization rate on pond phosphate concentrations, chlorophyll a, and fish growth in carp polyculture

Abstract: The effect of different application rates of triple superphosphate (22.4, 44.8, and 67.2 kg P2O5 ha−1) was observed on total and available phosphorus concentrations in pond soil, total and filterable orthophosphate concentrations in pond water, chlorophyll a, and fish growth in a carp polyculture system during summer (22–32°C) months to determine the economical dose of P2O5. pH, hardness, calcium and alkalinity of soil and water did not differ significantly among treatments (P > 0.05) and were within the desired ranges. Average total phosphorus concentrations in pond soil were not significantly different between treatments but available phosphorus (P > 0.05) in pond soil, total phosphorus (P > 0.001), and filterable orthophosphate (P > 0.0001) concentrations in pond water, chlorophyll a (P > 0.0001), and net fish production (P > 0.01) were significantly higher in fertilized ponds than in controls. Overall, fish yield did not significantly differ among treatments, suggesting that a very high dose of P2O5 may not be necessary for high yields. Reducing the dose of P2O5 could reduce cost without reducing fish production.

Polyculture of Nile Tilapia, Oreochromis niloticus, Either Confined in Cages or Unconfined in Freshwater Prawn, Macrobrachium rosenbergii, Ponds

Abstract: Polyculture of Nile tilapia, Oreochromis niloticus, confined in cages suspended in prawn, Macrobrachium rosenbergii, ponds has been shown to reduce phytoplankton densities, pH levels, and increase prawn production when compared to prawn monoculture ponds. However, as filter feeders, tilapia grazing might be more efficient if allowed free access to all portions of the water column, positively impacting both phytoplankton control and tilapia growth. This study was designed to compare the effects of confined and unconfined tilapia, in polyculture with freshwater prawns, on prawn growth, tilapia growth, algae populations, and water quality. Juvenile prawns were stocked into each of nine, 0.04 ha ponds as 60 d nursed juveniles (0.8 ± 0.3 g) at 62,000/ha. Three control ponds contained only prawns (MONO). In three other ponds, monosex (male) Nile tilapia (89.2 ± 23.6 g) were stocked unconfined into three ponds at 4400/ha (POLY-UNC). In three additional ponds, the same size and number of tilapia were stocked but confined in two, 1 m3 cages at 100 fish/cage (POLY-CON). Prawns were fed a sinking pellet (28% protein) twice daily at a standardized rate for 114 d. Tilapia were fed a floating pellet (32% protein) twice daily to apparent satiation for 106 d. In the POLY-UNC treatment, average prawn harvest weight (26 g) and prawn production (1625 kg/ha) were significantly lower (P 0.05) between the MONO and POLY-CON treatments in terms of prawn harvest weight, production and feed conversion ratio with combined averages of 38 g, 2465 kg/ha, and 1.9, respectively. Average harvest weight and production of adult tilapia were not significantly different (P > 0.05) in the POLY-CON and POLY-UNC treatments averaging 485 g and 2293 kg/ha, respectively. Tilapia in the POLY-CON treatment had a significantly higher (P 0.05) among water quality variables or phytoplankton populations. Lower prawn production in the POLY-UNC is likely due to competition for food with the large number of tilapia juveniles. Despite the use of Genetically Modified Tilapia (GMT) monosex males, several cohorts of juvenile tilapia were produced in each of the POLY-UNC ponds, resulting in over 2500 kg/ha of juveniles in the POLY-UNC treatment. No wild spawn tilapia juveniles were found in the POLY-CON ponds. In summary, confinement of tilapia in cages appears preferable when tilapia are polycultured with freshwater prawn.

Effects of selective harvesting and claw ablation of all-male freshwater prawn (Macrobrachium rosenbergii) on water quality, production and economics in polyculture ponds.

Abstract: The eiects of selective harvesting (SH) and claw ablation (CA) of blue-clawed (BC) prawns on an all-male freshwater prawn^¢n¢sh polyculture system were compared with control (Co) in quadruplicate. Ponds were stocked with all-male freshwater prawn Macrobrachium rosenbergii ,s ilver carpHypophthalmichthys molitrix ,c atlaCatla catla and mola Amblypharyngo

Impact of phased harvesting on population structure, feed intake pattern and growth performance of Macrobrachium rosenbergii DeMan (giant freshwater prawn) in polyculture with carps in concurrent rice–fish culture

Abstract: This study was carried out to study the impact of phased harvesting on the population structure, feed intake pattern and growth performance of Macrobrachium rosenbergii in polyculture with carps in a deepwater rice–fish system. There were two experimental conditions—rice–fish culture with phased harvesting (T1) and rice–fish culture without phased harvesting (T2)— and a control, which consisted of rice monoculture without fish (T3). In the T1 trial, 61% of the population had a mean body weight (MBW) 80 g in the T1 trial, while none of the population reached a MBW >80 g in the T2 trial. The removal of fast-growing individuals in T1 improved the prospects of other smaller individuals to achieve their individual growth potential. This step also disrupted the continuation of the socially induced differential growth rates, resulting in a wide variation in size within the population over time. The matrix of dietary overlap(s) of cultured species revealed that the degree of food preference was more similar between Cyprinus carpio and M. rosenbergii (0.9), while it overlapped poorly between Catla catla and M. rosenbergii (0.42). This high similarity index between bottom dwellers is evidence of the strong possibility that these bottom dweller compete for food. Natural and supplemental feed together with phased harvesting boosted the production of freshwater prawns (550 kg ha−1) in the T1 trial, while a 11.3% reduction in production was recorded in the T2 trial.

Polyculture Of Heteroclarias / Tilapia Under Different Feeding Regimes

Abstract: Triplicate Treatments of Heteroclarias and Nile Tilapia (Oreochromis niloticus) fingerlings in a semi-intensive polyculture system, were fed for twelve weeks on Pigeon pea meal, Bambara groundnut meal and coppen floating feed. They were fed at 3% body weight and were used as the control treatment. Growth performance and Physiochemical Parameters were measured weekly. Results showed that the treatment fed with coppen had the best growth performance; mean weight gain (2.23g) and (1.13g) for Heteroclarias and Tilapia, while the treatments fed with substitutes, showed appreciable growth performance with Pigeon pea meal having a final mean weight gain of (1.16g) and (0.74g) and Bambara nut coming last with (0.92)g and (0.97g) respectively. There was significant difference (P>0.05) between the feed types on the growth of the fish. (New York Science Journal 2010;3(10):42-57). (ISSN: 1554-0200).

The effect of chemical and organic fertilization on Phytoplankton and fish production in carp (Cyprinidae) polyculture system

Abstract: This study reports the effects of sheep and pig liquid manure, and chemical fertilizer on the phytoplankton, primary productivity and aquaculture production in the cultivation of carp in semi-rustic ponds The total yield was 4632 kg in two hectares Treatment with chemical fertilizers was found to present the highest yield with 1006 ± 067 (kg/Ha/day), followed by treatment with pig manure (827± 124 kg/Ha/day) and sheep manure (633 ±195 kg/Ha/day) It was also found that concentrations of phytoplankton were significantly (p<005) higher in ponds fertilized with sheep and pig manure (945940 and 1,157,706 cells/ml, respectively) than in ponds where chemical fertilizer was used (744560 cells/ml) In general, conditions were adequate to obtain high yields without commercial feed, thus organic fertilizer application can be recommended because ofits availability and low cost

Studies on the Effects of Polyculture of Litopenaeus vannamei with Portunus trituberculatus

Abstract: The study was designed and conducted to optimize the structure of polyculture for shrimp Litopenaeus vannamei with crab Portunus trituberculatus,and to compare their ecological efficiencies and water quality parameters.The experiments were conducted with land-based enclosures(5×5 m) setting in an earthen pond,in which crabs were stocked at a density of 6 ind·m-2 with shrimps at six different densities of 0,15,45,75,105 and 135 ind·m-2 respectively.The results showed that all the poly-culture treatments were superior to crab mono-culture treatment in survival rate,final size and net production.The highest survival rate,final size and net production of shrimp were 45.71%,43.22 g·ind-1 and 1 191 kg·hm-2 for the treatment of 45 ind·m-2,followed by 44.58%,39.13 g·ind-1 and 1 050 kg·hm-2 for the treatment of 75 ind·m-2,and the lowest were 35.13%,32.87 g·ind-1 and 693 kg·hm-2,which occurred in crab mono-culture treatment during the experimental duration of 60 d.The final size and survival rate had negative correlation with their stocking density.The concentrations of TAN,NO2-N,NO3-N and TN in poly-culture were higher than those in crab mono-culture significantly,and the concentrations of those were increased with the shrimp stock density significantly at the end of the culture period.The concentration of TAN in all poly-culture treatment was above 500 μg/L after 50 d.The treatment giving the best culturing benefit was crabs at 6 ind·m-2 and shrimps at 45-75 ind·m-2.

Pesticides et polyculture d'étang : de l'épandage sur le bassin versant aux résidus dans la chair de poisson

Abstract: Dam pond is connected to its watershed Use of pesticides on watershed may lead to dissipation in the environment Transfer of registered pesticides remains poorly studied Thus, the main objective of this work was to improve knowledge about the fate of pesticides in polyculture pond, especially contamination of fish flesh Five sites, each site corresponding to a pond and its watershed, were characterized They are placed on a gradient of crop proportion ranging from 0% to 85% of the watershed area The sum of quantified molecules in water ranged from 017 to 881 µg / L The biological response of fish, assessed by evaluation of eight biomarkers (EROD, CYP 3A, GST, CAT, SOD, GSH, GPx, and AChE), establish differences between species and sites studied A study of 14 targeted pesticides was conducted by a multi-residues method in water, sediments and fish flesh Isoproturon (maximum value 269 µg/L) and metazachlor (maximum value 054 µg/L) are the main contaminants in water; Trifluralin (05 to 13 µg/kg PS) and isoproturon (07 to 564 µg/kg PS) in sediments Trifluralin, isoproturon, carbendazim and metazachlor (maximum values of 21, 075, 013 and 02 µg/kg PF, respectively) are quantified in muscle of fish Low levels observed in fish can be explained by a low potential to bioaccumulate (measured ex-situ for some molecules, between 10-6 and 10-3) However, half-lives in the muscle may be several weeks depending, explaining the possibility to find molecules in fish flesh Finally, many factors, particularly related to site characteristics (uncontrollable) and management practices (upgradable), influence profile of pesticides in muscle and biological responses of fish

Effect of Different Treatments on the Periphyton Quantity and Quality in Experimental Fishponds

Abstract: Periphyton development and composition were studied in three different treatments: (i) two fishpond units of wetland-type wastewater treatment pond systems, (ii) two fishponds in combined intensive-extensive fish farming systems and (iii) three traditional polyculture fishponds. Results showed that amounts of periphyton developed in traditional polyculture fishponds (iii) were different compared to the other treatments (i and ii), where the main function of ponds was stated wastewater treatment. Negative correlation was also observable between water quality parameters and periphyton production. The lower trophity, halobity and saprobity level of ponds indicated higher amount of periphyton. The dry matter content of periphyton was significantly higher in the samples, which were developed in traditional polyculture fishponds (2.84±3.02 g m −2 day -1 , whereby the ash content in dry matter 74%), than samples taken from (i) (1.60±2.32 g m -2 day -1 , 61%) and (ii) fishponds (0.65±0.45 g m -2 day -1 , 81%).

Ecological polyculture method for portunus trituberculatus mainly cultured in pond

Abstract: The invention discloses an ecological polyculture method for portunus trituberculatus mainly cultured in a pond The method is characterized by comprising the steps of cleaning the pond, culturing ruditapes philippinarum, fenneropenaeus chinensis and the portunus trituberculatus, feeding bait and the like By using ecological complementarity of the ruditapes philippinarum, the fenneropenaeus chinensis and the portunus trituberculatus for polyculture, the method of the invention fully utilizes the natural bait, increases the spatial stratification of the ecological structure of the culture pond, improves the stability of the environment of the culture pond and solves the problems of cannibalism of the portunus trituberculatus, insufficient bait, diseases, degradation of water quality and the like during the culturing, so that the technical effects of high yield, high efficiency and environmental protection are realized

Farming of the Juvenile Narrow-clawed Crayfish ( Astacus leptodactylus ) in Cages and Ponds in Polyculture With Fish in the Heated Waste Water of the Thermal Power Plant

Abstract: Experimental research has been carried out on fanning of the narrow-clawed crayfish larvae in ponds and cages in the TPP waste water. It was shown that farming in such conditions during the first vegetation period was more effective, than in water bodies with natural temperature regime. In ponds in polyculture with fish crayfish summerlings reached 4.4-4.6 cm length and 2.69-3.34 g mass; when grown in cages with natural forage resources - 3.4-3.7 cm and 1.25- 1.53 g, accordingly. Survival rate in the ponds amounted to 2.9-3.0%, in cages - 22.037.3%. Density of seeding should be about 70 specimens/m 2 . Cages of the open-air type have been recommended.

Density effects of silver carp Hypophthalmichthys molitrix and catla Catla catla on the production system in all-male freshwater prawn-finfish polyculture ponds

Abstract: The effects of three different combinations of silver carp Hypophthalmichthys molitrix and catla Catla catla density on the production system in all-male freshwater prawn–finfish polyculture ponds were evaluated in triplicate The stocking density of silver carp and catla, respectively, were maintained at 2000 and 500 ha−1 in treatment SC2000C500, 1500 and 1000 ha−1 in treatment SC1500C1000 and 1000 and 1500 ha−1 in treatment SC1000C1500 Male freshwater prawn Macrobrachium rosenbergii and small fish mola Amblypharyngodon mola densities were fixed in all treatments at 12 000 and 20 000 ha−1 respectively Management practices were same for all treatments Blue-clawed male prawns were harvested twice during the 122-day culture at 15-day intervals before the final harvest Plankton and macro-benthos abundance and water quality parameters (except transparency and chlorophyll a) did not vary significantly (P>005) among treatments Mean final weights of both silver carp and catla were decreased with the increasing of their own stocking density The treatment SC1500C1000 resulted in 25–32% increased net production of silver carp plus catla (461 kg ha−1) and 20–21% increased net production of all species combined (874 kg ha−1) as compared with the other treatments, although the differences in production of prawn and mola among treatments were not significant

Managing the Interactions Between Plants and Animals in Marine Multi-Trophic Aquaculture

Abstract: China has long been known for manure-based integrated multiple species fish farming technology. Commonly known as “polyculture,” this traditional Chinese system is practiced in pond aquaculture where several fish species are reared together, creating a multi-output production structure. For example, polyculture of carps with animal and plant husbandry is based on the efficient utilization of organic manures in the ponds. Typically, the manures are supplied from animal and poultry houses built directly over the ponds at the edge, or from large numbers of ducks allowed to swim freely on the ponds. All these practices have been common in China for centuries and have long since been adopted by other countries in Asia and Central Europe. In Israel and several Central Europe countries, cattle and pig manures and litter from poultry houses are also transported from external animal houses and spread in the fish ponds (Billard, 1995).

Influence of different dietary protein levels and feeding frequencies on growth performance and feed utilization of the Giant freshwater prawn, Macrobrachium rosenbergii with the Nile tilapia, Oreochromus niloticus in polyculture

Abstract: n 84-day experiment was conducted to investigate the effects of two dietary protein levels 30 & 35% CP & three feeding frequencies 2, 3 & 4 times a day (8:0 and 11.0 h), (8.0, 11.0 and 14.0 h) and (8.0, 11.0, 14.0 and 17.0 h) on growth performance and feed utilization of the freshwater prawn, Macrobrachium rosenbergii with the Nile tilapia, Oreochromuis niloticus fry in a polyculture system. The experiment was conducted in small-scale hapas, 3.75 m -3 each in triplicates. Irrespective of polyculture system, prawn PL fed diet containing 35% CP 4 times a day had significant (P≤0.05) the highest final body weight (FBW), weight gain (WG), specific growth rate(SGR) and best feed conversion ratio (FCR) values among all treatments. Meanwhile, the Nile tilapia fed on diet containing 35% CP at 2 times/day recorded the highest significant FBW, WG, and best FCR among all treatments. The highest significant total biomass weight (kg hapa -1 ), and gain (kg hapa -1 ) and feed consumption (kg hapa 1 ) were obtained for prawn and tilapia feed the diet containing 35% protein. No significant differences (P≤0.05) were observed for SGR, FCR and S among all experimental hapas. The same trend was recorded for the different feeding frequencies. The highest values of the whole body CP, EE, ash and gross energy content were recorded for prawn fed on 30% diet at twice per day. No clear trend was observed for body composition of the Nile tilapia fry except for the highest lipid content (P ≤ 0.05) recorded for the fish fed on 30% CP diet 2 times per day. The findings of the current trials revealed that, feeding frequency has a great effect on growth performance and feed utilization efficiency of the freshwater prawn M. rosenbergii PL and the Nile tilapia fry. Feeding frequency 4 times per day for M. rosenbergii PL either 2 or 3 times per day for Nile tilapia fry is recommended under similar rearing condition to achieve best performance for both animals.

Model Polikultur Udang Windu (Penaeus monodon Fab), Ikan Bandeng (Chanos-chanos Forskal) dan Rumput Laut (Gracillaria Sp.) Secara Tradisional Traditional Polyculture Model of Black Tiger Prawn (Penaeus monodon Fab), Milk Fish (Chanos-chanos Forskal) and Seaweed (Gracillaria Sp.)

Abstract: Polyculture is an alternative to solving water quality problems leading to decrease of fish production in the ponds. The present research is aimed at establishing the management of

Analyses of Productivity of Nile Tilapia (Oreochromis niloticus), Red Tilapia (O. niloticus X O. mossambicus) and Pacific White Shrimp (Litopenaeus vannamei) Polyculture in a Recirculating System

Abstract: INTRODUCTION Current situation of world aquaculture Importance of shrimp-fish polyculture Characteristics of the involved fish and shrimp species in this study Dissertation format Description of the preliminary study Test of animals Results Discussion Present studies .. General discussion Conclusion References CHAPTER ONE: COMPARATIVE STUDY BETWEEN SIMULTANEOUS POLYCULTURE AND MONOCULTURE ON THE GROWTH PERFORMANCE OF PACIFIC WHITE SHRIMP (Litopenaeus vannamei) AND NILE TILAPIA (Oreochromis niloticus) AT DIFFERENT FEEDING RATES IN A RECIRCULATING SYSTEM Abstract Introduction Materials and methods Results Discussion References CHAPTER TWO: COMPARATIVE ANALYSIS BETWEEN POLYCULTURE AND MONOCULTURE SYSTEMS TO MEASURE THE EFFECT OF NILE TILAPIA (Oreochromis niloticus) ON THE PRODUCTION OF PACIFIC WHITE SHRIMP (Litopenaeus vannamei) IN A RECIRCULATING SYSTEM Abstract Introduction Materials and methods Page

Eco-simulation and Modeling of Monoculture and Polyculture Milkfish Farming in the Bolinao Area and Its Economic Analysis

Abstract: Scientific polyculture system is helpful to sustained development of sea. This paper models the impact of Milkfish farming on the local ecology in the Bolinao Area. Firstly, this paper simulates the current Milkfish monoculture farming by using the method of Lotka-Volterra, obtains a new method as Monoculture Farming Ecological Simulation. The new method is very practical by comparing the simulation results with the actual observation results. Then this paper establishes the method of polyculture farming based on the Ecological Dynamics to modify the current farming method. After simulating the polycuture farming and comparing its results with the monoculture farming’s, then obtains the conclusion that the modified farming method proved to be scientific and effective as it can improve the water quality and increase the economic income.

Developing culture technology of indigenous small fish species mola in aquaculture ponds in Sunderbans.

Abstract: To develop culture technology of indigenous small fish species mola in Aquaculture pond with carps and prawn, a trial with three treatments was conducted from July to December 2006 in 33 ponds, belonging to poor households in Sunderbans region, India. Rohu, mrigal, prawn and mola were stocked at 3,000 ha, 1,000 ha, 3,750 ha and 20,000 ha, respectively, in all ponds. Of the planktivorous carp species, silver carp was stocked at 2,500 ha, 1,750 ha and 1,000 ha and catla at 1,000 ha, 1,750 ha and 2,500 ha in treatment I, treatment II and treatment III, respectively. Before stocking, the ponds were treated with urea (50 kg ha), TSP (50 kg ha) and cow dung (1500 kg ha). Mustard oil cake and rice bran (1:2 ratio) were fed daily, at the rate of 3 per cent body weight. Mola was partially harvested several times throughout the production season. Mola production was highest with the highest stocking density of silver carp and lowest of catla. It may be concluded that mola-carpprawn polyculture may be a good option for rural farmers of the Southern region of West Bengal to reduce poverty and ensure household nutrition.

Effect of different treatments on the periphyton quantity and quality in experimental fishponds

Abstract: Periphyton development and composition were studied in three different treatments: (i) two fishpond units of wetland-type wastewater treatment pond systems, (ii) two fishponds in combined intensive-extensive fish farming systems and (iii) three traditional polyculture fishponds. Results showed that amounts of periphyton developed in traditional polyculture fishponds (iii) were different compared to the other treatments (i and ii), where the main function of ponds was stated wastewater treatment. Negative correlation was also observable between water quality parameters and periphyton production. The lower trophity, halobity and saprobity level of ponds indicated higher amount of periphyton. The dry matter content of periphyton was significantly higher in the samples, which were developed in traditional polyculture fishponds (2.84±3.02 g m −2 day -1 , whereby the ash content in dry matter 74%), than samples taken from (i) (1.60±2.32 g m -2 day -1 , 61%) and (ii) fishponds (0.65±0.45 g m -2 day -1 , 81%).

Comparative slaughtering analysis of two-summer old silver carp (hypophthalmichthys molitrix val.) reared under the conditions of integrated and non-integrated technologies сравнителен анализ на кланичните характеристики на двулетен бял толстолоб (hypophthalmichthys molitrix val.), отглеждан при традиционна и интегрирана с патици технологии

Abstract: A comparative slaughtering analysis has been carried out at the Institute of Fisheries and Aquaculture, Bulgaria upon two-summer old silver carp, reared in polyculture (H. molitrix 300 p-ces.ha -1 and C. carpio – 2000 p-ces.ha -1 ) under the conditions of integrated with ducks (Peking ducks and mule ducks) and non-integrated technologies. The fish in all experimental ponds have grown well and no considerable difference has been observed between the separate variants as regards the final live weight. The integration has exercised a positive (F=4.182; P<0.005) effect upon the slaughtering output, however, this effect has not been preserved as regards the relative fillet share within the fish carcass (F=0.096; P<0.05).