The basics of bio-flocs technology: The added value for aquaculture

Important operational changes that have gradually been assimilated and new approaches that are developing as part of the movement toward sustainable intensive aquaculture production systems are presented via historical, current, and future perspectives Improved environmental and economic sustainability based on increased efficiency of production continues to be realized As a result, aquaculture continues to reduce its carbon footprint through reduced greenhouse gas emissions Reduced use of freshwater and land resources per unit of production, improved feed management practices as well as increased knowledge of nutrient requirements, effective feed ingredients and additives, domestication of species, and new farming practices are now being applied or evaluated Successful expansion into culture of marine species, both off and on shore, offers the potential of substantial increases in sustainable intensive aquaculture production combined with integrative efforts to increase efficiency will principally contribute to satisfying the increasing global demand for protein and food security needs

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Achieving sustainable aquaculture: Historical and current perspectives and future needs and challenges

Total alkalinity and total hardness are familiar variables in aquatic animal production. Aquaculturists—both scientists and practitioners alike—have some understanding of the two variables and of methods for adjusting their concentrations. The chemistry and the biological effects of alkalinity and hardness, however, are more complex than generally realized or depicted in the aquaculture literature. Moreover, the discussions of alkalinity and hardness—alkalinity in particular—found in water chemistry texts are presented in a rigorous manner and without explanation of how the two variables relate to aquaculture. This review provides a thorough but less rigorous discussion of alkalinity and hardness specifically oriented toward aquaculture. Alkalinity and hardness are defined, their sources identified, and analytical methods explained. This is followed by a discussion of the roles of the two variables in aquaculture, including their relationships with carbon dioxide, pH, atmospheric pollution, ammonia, and other inorganic nitrogen compounds, phytoplankton communities, trace metals, animal physiology, and clay turbidity. Liming and other practices to manage alkalinity and hardness are explained. Changes in alkalinity and hardness concentrations that occur over time in aquaculture systems are discussed. Emphasis is placed on interactions among alkalinity, hardness, water quality, and aquacultural production.

Alkalinity and Hardness: Critical but Elusive Concepts in Aquaculture

https://smalllab.siu.edu/wp-content/uploads/2012/10/Effect-of-isoeugenol-sedation-on-plasma-cortisol-glucose-and-lactate-dynamics-in-channel-catfish-Ictalurus-punctatus-exposed-to-three-stressors..pdf

Effect of isoeugenol sedation on plasma cortisol, glucose, and lactate dynamics in channel catfish Ictalurus punctatus exposed to three stressors

Dissolved oxygen is an important index to evaluate water quality, and its concentration is of great significance in industrial production, environmental monitoring, aquaculture, food production, and other fields. As its change is a continuous dynamic process, the dissolved oxygen concentration needs to be accurately measured in real time. In this paper, the principles, main applications, advantages, and disadvantages of iodometric titration, electrochemical detection, and optical detection, which are commonly used dissolved oxygen detection methods, are systematically analyzed and summarized. The detection mechanisms and materials of electrochemical and optical detection methods are examined and reviewed. Because external environmental factors readily cause interferences in dissolved oxygen detection, the traditional detection methods cannot adequately meet the accuracy, real-time, stability, and other measurement requirements; thus, it is urgent to use intelligent methods to make up for these deficiencies. This paper studies the application of intelligent technology in intelligent signal transfer processing, digital signal processing, and the real-time dynamic adaptive compensation and correction of dissolved oxygen sensors. The combined application of optical detection technology, new fluorescence-sensitive materials, and intelligent technology is the focus of future research on dissolved oxygen sensors.

Review of Dissolved Oxygen Detection Technology: From Laboratory Analysis to Online Intelligent Detection.

Feed-based production of ictalurid catfish in ponds is the largest aquaculture sector in the USA. Feed has an oxygen demand, and increases carbon dioxide, ammonia nitrogen, and phosphate inputs to ponds. Major sources of oxygen in ponds are phytoplankton photosynthesis and mechanical aeration; the major sink for oxygen is respiration by fish and by microorganisms in the water column and sediment. Dissolved oxygen concentrations decline when respiration exceeds photosynthesis, and the most crucial time for low dissolved oxygen concentration is at night. Mechanical aeration is applied to avoid nighttime dissolved oxygen concentrations from falling below the critical level for catfish of 3 mg/L. Electrically powered paddlewheel aerators are used by most catfish producers. The oxygen-transfer efficiency of these aerators is known, but calculations of aeration requirement from stocking and feeding rates are not reliable because of variation in phytoplankton abundance and in weather conditions. Dissolved oxygen concentrations must be monitored, and when measurements suggest that nighttime dissolved oxygen concentration will be unacceptably low, tractor-powered emergency aerators must be operated to supplement dedicated aeration. Dissolved oxygen concentration also is important in hatcheries, and small aeration systems have been developed for hatchery application.

Dissolved Oxygen and Aeration in Ictalurid Catfish Aquaculture

Aeration allows for higher feeding rates and increased production of channel catfish Ictalurus punctatus in intensive and semi-intensive aquaculture systems. However, the effect of specific dissolved oxygen (DO) concentrations on various production parameters remains unknown. The purpose of this 2-year study was to determine the effect of daily minimum DO concentration on channel catfish production. Six 0.1-ha ponds were each equipped with three 0.37-kW (0.5-hp) aerators and one 0.37-kW circulator. Dissolved oxygen concentrations were monitored and recorded with a commercial oxygen monitor that also controlled aeration. During both years, aeration in the high-oxygen treatment was initiated when the DO concentration dropped below 5.0 mg/L (mean, 64% saturation from May to September); aeration in the low-oxygen treatment was initiated when the DO concentration dropped below 2.5 mg/L (32% saturation; 2001) or 1.5 mg/L (19% saturation; 2002). The minimum DO concentrations resulting from this aeration...

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Effect of Oxygen Management on Culture Performance of Channel Catfish in Earthen Ponds

Economics of alternative catfish production technologies

This study determined the effects of the minimum daily dissolved oxygen (DO) concentration on the production parameters of channel catfish Ictalurus punctatus in earthen ponds. Fifteen 1-acre ponds (five ponds per treatment) were managed as high-oxygen (minimum DO concentrations averaging 4.37 ppm or 54% air saturation from June through September), medium-oxygen (minimum DO concentrations averaging 2.68 ppm or 33.2% air saturation), or low-oxygen treatments (minimum DO concentrations averaging 2.32 ppm or 28.7% air saturation) using one 5-hp electric paddlewheel aerator per pond. Fish in the high-, medium-, and low-oxygen treatment ponds were fed a mean total of 14,008, 13,212, and 12,607 lb/acre of 28%-protein floating feed, respectively. Net production paralleled the total amount of feed fed, averaging 5,772, 5,278, and 5,113 lb/acre in the high-, medium-, and low-oxygen treatments, respectively. Individual fish weight at harvest also showed a similar trend, averaging 1.37, 1.33, and 1.30 lb in...

Eugene L. Torrans

Papers

Dissolved Oxygen and Aeration in Ictalurid Catfish Aquaculture

Effect of Oxygen Management on Culture Performance of Channel Catfish in Earthen Ponds

Economics of alternative catfish production technologies

Production Responses of Channel Catfish to Minimum Daily Dissolved Oxygen Concentrations in Earthen Ponds

Partitioned pond aquaculture systems.