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International Journal of Recirculating Aquaculture, Volume 1 Complete Issue
(Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
The International Journal of Recirculating Aquaculture presents research and applications expertise in the area of recirculation systems. This journal is intended to be a forum for the open exchange of reliable information on the subjects of recirculating aquaculture. The industry of recirculating aquaculture requires expertise from many different fields such as animal husbandry, economics, water chemistry, and systems engineering. The following papers focus on a variety of topics, with recirculation as the common element.
Effects of High-density Stocking in a Recirculating Aquaculture System on Gill Morphology ofHybrid Striped Bass (Morone saxatilis x M. chrysops)
Smith, B. J.; Smith, Stephen A.; Pfeiffer, Carl J. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
The types and distribution of gill lesions observed in hybrid striped bass (Morone saxatilis x M. chrysops) reared in a commercial-scale recirculating aquaculture system are described. When placed in the system as fingerlings and reared there for eight months at typical stocking density, the gills of all examined fish presented a variety of extensive, non-specific lesions typically resulting from poor water quality. Lesions included epithelial cell hyperplasia, infiltration of the interfilamental region by mixed inflammatory cells, hyperplasia of mucous and lamellar epithelium, lamellar fusion and occasional filamental fusion. Up to 76% of the gill sample surface of individual fish was affected, with lesions being most severe in the distal filamental regions. Fish transferred to and maintained at low stocking densities in water of superior quality demonstrated that all lesions were fully reversible by five weeks post-transfer. This study demonstrates that culture of hybrid striped bass under intensive aquaculture management induced pathological changes in the gills, and suggests that maintenance of fish under improved water quality conditions will reduce gill lesions, which could potentially increase the fishes' performance.
Hematology and Plasma Chemistry Values for Production Tilapia (Oreochromis hybrid) Raised in a Recirculation System
Hrubec, T. C.; Smith, Stephen A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
Tilapia are a frequently aquacultured fish, yet little is known about their normal physiology and response to disease. To assess specific diseases in mammals, blood constituents are routinely analyzed and compared to previously determined standardized values. Research to establish hematologic values for normal healthy fish is required before blood analysis can be used for diagnostic purposes in fishes. This study determined hematology and plasma chemistry values for production tilapia (Oreochromis hybrids) raised in a recirculation system. Using standard clinical techniques, the following hematologic parameters were determined: PCV (packed cell volume), plasma protein and MCV (mean cell volume) values; and erythrocyte, leukocyte, lymphocyte (small and large), neutrophil, monocyte, eosinophil, thrombocyte-like-cell, and thrombocyte numbers. Additionally, the following plasma chemistry values were determined: total protein, albumin, globulin, creatinine, total bilirubin, ALP (alkaline phosphatase), AST (aspartate aminotransferase), sodium, potassium, chloride, calcium, phosphorus, magnesium, glucose, cholesterol, ammonia and osmolality. Analysis of blood parameters can enhance production of hybrid tilapia by providing a means for the early detection of infectious diseases, and by assisting in the identification of sub-clinical conditions affecting production performance.
Economic Analysis of an Aquaponic System for the Integrated Production of Rainbow Trout and Plants
Adler, P. R.; Harper, J. K.; Takeda, F.; Summerfelt, S. T. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
Conventional treatment alternatives for phosphorus in wastewater, whether they employ chemical precipitation, physical removal, or land application technologies, represent a significant additional cost to the owner of an aquaculture operation. Plant-based removal of nutrients has the potential to generate additional revenues, which can offset treatment costs. The objective of this analysis was to describe the economic relationship between a 22,680 kg per year recirculating rainbow trout (Oncorhynchus mykiss Walbaum) production system and a hydroponic treatment unit, growing 'Ostinata' lettuce (Lactuca sativa L.) and sweet basil (Ocimum basilicum L.), capable of reducing phosphorus concentration levels in the fish farm effluent to less than 0.1 mg/L. The integration of the fish and plant production system (aquaponics) produces economic cost savings over either system alone. Shared cost savings come from spreading out operating costs (e.g., management, water, nutrients, and overhead charges) and capital costs (e.g., backup generator, used truck, and office equipment) over the two systems. The investment analysis demonstrates the profitability of this combined system over its 20-year expected life. Net present values are positive for a wide range of discount'rates. Internal rate of return analysis shows that for a total investment of $244,720 this system can potentially provide a return of 12.5%. The hydroponic system drives the potential profitability of the combined system with 67% of annual returns derived from plant production.
Effects of Selected Chemotherapeutants on Nitrification in Fluidized-Sand Bioftlters for Coldwater Fish Production
Schwartz, M. F.; Bullock, G. L.; Hankins, J. A.; Summerfelt, S. T.; Mathias, J. A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
Four fish chemotherapeutants, formalin, benzalkonium chloride, chloramine-T, and hydrogen peroxide were evaluated for their effect on the nitrification efficiency of fluidized-sand biofilters. The chemotherapeutants were added at conventional concentrations to two small-scale (2,200 L) coldwater recirculating rainbow trout (Oncorhynchus mykiss) culture systems each containing six fluidized-sand biofilters operating in parallel. Nitrification efficiency of biofilters was calculated before and after chemotherapeutant treatments by determining ammonia removal efficiency at ambient conditions, and also when challenged with a sudden increase of ammonium chloride at a concentration four times that of the ambient total ammonia-nitrogen (TAN). Two formalin treatments in recycle bath mode at 167 and 300 ppm were conducted with only the 300 ppm treatment having a significant negative effect on biofilter nitrification efficiency. Four single benzalkonium chloride treatments of one and 2 ppm were conducted; two static bath treatments and two recycle bath treatments. Of these four tests, only the recycle bath treatments caused biofilter nitrification efficiency to be significantly impaired. Two multiple treatments with benzalkonium chloride were conducted: one static bath treatment and one recycle.bath treatment. These treatments caused ammonia removal efficiency to decrease by 18% in the static bath treatment and by 63% in the recycle bath treatment. Of these two tests, only the recycle bath treatment caused a significant impairment of nitrification. Single static bath and recycle bath treatments with 9 ppm of chloramine-T both resulted in significant impairment of nitrification, as did a 12 ppm multiple static bath treatment. A single static bath treatment with 100 ppm of hydrogen peroxide caused almost total failure of nitrification within 24 h of treatment but biofilters were able to remove 23% of TAN within 48 h of treatment.
Comparison of Growth, Feed Conversion and Survival of Morone saxatilis female x M. mississippiensis male and M. saxatilis female x M. chrysops male Hybrids Reared in Recirculating Aquaculture Systems
Bosworth, B. G.; Libey, George S.; Wolters, W. R. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
Striped bass female (M. saxatilis) x white bass male (M. mississippiensis), (SBxWB, n = 300) and striped bass female x yellow bass male (M. chrysops) (SBxYB, n = 300) fingerlings, initial mean weight 91 g and 62 g, respectively, were reared in recirculating aquaculture systems at densities of 118 fish/m3 for 120 days. Mean weight increased 309 g and 151 gin SBxWB and SBxYB, respectively. ,final mean weight and total length, and rate of weight and length increase were higher for SBxWB than SBxYB. Condition factor and survival were higher for SBxYB (1.04 and 99.3%, respectively) than for SBxWB (1.01 and 96.0%,respectively). Mean feed conversion ratio (FCR) was lower for SBxWB (1.4) than for SBxYB (1.6). Significant time x hybrid interactions indicated that growth rate of SBxYB improved, relative to SBxWB, as the study progressed. Positive linear trends for total ammonia, unionized ammonia, and nitrite indicate water quality deteriorated as the study progressed. Time x hybrid interactions for growth rate may have been due to differential responses of SBxYB and SBxWB to deterioration of water quality. Although SBxYB had slightly better survival than SBxWB and their growth rate improved relative to that of SBxWB, the slow overall growth of SBxYB limits its potential for recirculating system production.
An Overview of Design Considerations for Small Recirculating Fish Culture Systems
Harmon, T. S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
Aquatic system engineering is an important factor when designing a new fish holding system or renovating an existing system. Indoor recirculating aquatic systems may be used for various operations, some of which may include: the quarantine of new animals, isolation for ill fish, aquaculture, research, or as educational displays. Professional engineers generally design large or high-density systems using a massbalance approach. However, smaller systems are typically designed or renovated by their immediate owners, which may include aquaculturalists, aquarists, biologists, zoologists, or professors. In many instances trial and error is used to size the equipment, which can get very expensive and take up valuable time. Undersized or oversized equipment wastes electricity and possibly reduces the life of the equipment. These limitations can be avoided by using the practical guidelines given here and taking into consideration a few simple design factors. Proper design of these systems can be accomplished by much quicker methods than a full-scale mass-balance approach and will typically work for low-density systems.
Hematology and Serum Chemistry Values for Winter Flounder (Pleuronectes americanus)
Dye, V. A.; Hrubec, T. C.; Dunn, J. L.; Smith, Stephen A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
Clinical analysis of blood to determine hematology and plasma biochemistry values is routinely used to assess the health of wild and domestic animals. Flounder culture is a fast growing segment of the U.S. aquaculture industry and tools are needed to monitor the health of these fish. This paper reports a complete hematologic and blood biochemistry profile for normal healthy winter flounder, Pleuronectes americanus, maintained in recirculated artificial seawater. The following hematologic values were determined: Packed cell volume, plasma protein, erythrocyte number, hemoglobin, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, and leukocyte, lymphocyte, neutrophil, monocyte, and thrombocyte numbers. A description of leukocyte morphology is presented. Additionally, the following serum biochemical values were determined: Total protein, albumin, globulin, sodium, potassium, chloride, calcium, phosphorus, magnesium, glucose, blood urea nitrogen, creatinine, total bilirubin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, cholesterol and triglycerides. Analysis of blood parameters can enhance flounder culture by providing a means for the early detection and identification of infectious disease and of sub-lethal conditions affecting production performance.
International Journal of Recirculating Aquaculture, Volume 2 Complete Issue
(Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
The International Journal of Recirculating Aquaculture presents research and applications expertise in the area of recirculation systems and technology. This journal is intended to be a forum for the open exchange of reliable information on the subjects of recirculating aquaculture. The industry of recirculating aquaculture requires expertise from many different fields such as animal husbandry, economics, water chemistry, waste managment, food safety, genetics, and systems engineering. The following papers focus on a variety of topics, with recirculation as the common element.
Growth and Production Characteristics of Palmetto Bass (Morone saxatilis female x Morone chrysops male) Reared at Three Densities in a Pilot-scale Recirculating Aquaculture System
Brazil, B. L.; Nunley, Chad E.; Libey, George S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
Production characteristics of palmetto bass (Morone saxatilis female x Morone chrysops male) reared at three stocking densities (36 fish/m3, 72 fish/m3, and 144 fish/m3) in a pilot-scale RAS were evaluated. A final mean ±SE fish weight of 412.1 ± 7.8 g at the high density was significantly lower than that of fish at the medium density weighing 542.1 ± 11 .8 g (P < 0.05). Fish weight (676.1 ± 17 .0 g) at_ the lowest density was significantly higher than at the high and medium densities (P < 0.05). The average daily weight gain at the low density (2.8 g/d) was 22% and 47% higher than fish reared at the medium and high densities, respectively. Total biomass gains of 733.8, 483.3, and 297.9 kg were obtafued at the high, medium, and low densities. Feed conversion and survival rates were similar among densities averaging 1.4 and 97 .1 %, respectively. Higher mean daily and cumulative feed totals at the highest density contributed to significantly higher ammonia and nitrite concentrations and lower pH levels at haryest. All other measured water quality parameters were similar among densities and remained within known acceptable limits for fish growth. The results indicated that palmetto bass reared in closed systems reached market size in 224 days at the low and medium densities. However, the relative biomass production may not justify such strategies when compared to the yield obtained at the highest rearing density.
Book Review: Food Intake in Fish
Craig, Steven R. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
As the field of fish nutrition continues to grow and flourish, current reference texts updated with the latest and most relevant references are becoming more important and necessary. Food Intake in Fish, edited by Dominic Houlihan, Thierry Boujard and Malcolm Jobling is an excellent addition to the library of anyone involved in the culture of, or experimentation with fish...
International Journal of Recirculating Aquaculture, Volume 3 Complete Issue
(Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
The International Journal of Recirculating Aquaculture presents research and applications expertise in the area of recirculation systems and technology. This journal is intended to be a forum for the open exchange of reliable information on the subjects of recirculating aquaculture. The industry of recirculating aquaculture requires expertise from many different fields such as animal husbandry, economics, water chemistry, waste managment, food safety, genetics, and systems engineering. The following papers focus on a variety of topics, with recirculation as the common element.
A Low Cost Bar Grader for the Harvest of Hybrid Striped Bass (Morone chrysops x M. saxatilis)
Easter, C. C.; Helfrich, Louis A.; Tate, A.; Libey, George S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Four bar graders were designed and built to separate a mixed-size population of market-size reciprocal cross hybrid striped bass Marone chrysops x M. saxatilis in rectangular culture tanks in an indoor, recirculating aquaculture system. Grader frames were constructed of 5.1 cm (2 inch) PVC pipe and fittings. PVC electrical conduit ( 1.27 cm, 0.5 inch) was used to form a series of parallel, equally spaced vertical bars within the frame. Bar slot spaces were 1.90, 2.54, 3.20, or 3.80 cm (0.75, 1.0, 1.25, 1.5 inches). A strip of flexible vinyl siding was attached to the outer edges of the bar grader to permit a tight fit between the grader and tank walls, and prevent fish from swimming around the grader. The graders were placed sequentially into one end of the tank, largest slot size first, and maneuvered to the opposite end. Each grader remained in the tank for 60 min. Fish too large to pass through a grader were netted and measured for weight, length and width. Regression analysis was performed for average weight retained at each bar spacing (Y = 7.13619 + 0.070716 X; r2 = .9987). By rearrangement, an equation was derived which allows a culturist to select a bar spacing that retains fish of a predetermined weight: Grader bar slot size (mm)= Fish weight (g) -177.9 / 31.7). Construction of each grader required approximately 2 h, and materials cost $20.
Book Review: Practical Genetics for Aquaculture
Lutz, C. G. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Comparisons of Tilapia Seed Production Under Various Broodstock Densities and Fry Stocking Densities
Glenney, G. W.; Libey, George S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Three types of seed (eggs, sac-fry, and fry) production for Rocky Mountain White® hybrid tilapia, (O. niloticus x O. aureus), were compared under green water conditions over a six-month period in an environmentally-controlled greenhouse at the Virginia Tech Aquaculture Center. Rectangular tanks were stocked with broodstock (mean wt. 680 g), at a sex ratio of 3 females to 1 male. Nine tanks were stocked at one of three densities (1, 2, and 4 females/m2), and seed was collected from the females' mouths weekly. Three additional tanks were stocked at a density of 2 females/m2, and fry were collected from the edges of the tanks daily. Average number of viable fry produced by the clutch removal method at 1 female/m2 was significantly higher than the combined average production of densities at 2 and 4 females/m2 (p< 0.02). Even though there was no significant difference between viable fry production per meter sq. (p>0.05), the highest density consistently produced more fry/m2. No significant difference was observed in viable fry production between the clutch removal method and the natural mouth-brooding method (p>0.05). The mean monthly hatchery seed survival was 65.7 ± 2.3%, which varied largely depending on initial seed developmental stage. The effects of stocking density on growth and survival were evaluated by stocking 14-16 day old artificially incubated fry (25.5 ± 0.32 mg, 12.1 ± 0.04 mm), into 150-liter troughs at three densities (3, 6, and 12 fry/ liter) under green water conditions for 30 days. Significant differences were observed between mean weight, length, survival, and feed conversion ratios among the various fry stocking densities (p<0.05).The greatest growth was at a density of 3 fry/liter, while survival was not affected until a density of 12 fry/liter was reached. These results suggest that to maximize fry production and reduce labor, a density of 4 females/m2 or higher be used under the natural mouth-brooding seed collection method. They also suggest a fry stocking density between 6 to 12 fry/liter should be used with periodic grading or sex reversal to reduce cannibalism and increase growth.
Evaluation of UV Disinfection Performance in Recirculating Systems
Zhu, S.; Saucier, B. B.; Chen, S.; Durfey, J. E. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
The use of ultraviolet (UV) disinfection devices has become increasingly popular in wastewater and aquaculture industries. Although the effectiveness of UV disinfection has been well documented for flowthrough operation regimes in wastewater treatment, research focusing on water recirculating systems is still limited. In this study, the performance of single-lamp UV devices were tested on a recirculating system for fecal coliform (FC) disinfection. Experimental results indicated that UV power input, recirculating flow rate and water UV transmittance were three important factors determining UV disinfection efficiency. An UV disinfection model for a recirculating system was developed based on theoretical analysis and experimental data. A key model parameter, namely the first-order inactivation rate constant (k), was determined to be 0.0062 m2 J-1 for FC disinfection. Simulation using the model provided useful information for design and operation of recirculating UV disinfection systems. The model prediction of disinfection process for other microorganisms is also capable of using reported values of the inactivation rate constant.
Water Quality Impacts of Three Biofilter Designs in Recirculating Aquaculture Systems
Hall, A. G.; Hallerman, Eric M.; Libey, George S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Nine recirculating aquaculture systems utilizing three biofilter types were placed on line and stocked with yellow perch, Percaflavescens, fingerlings. Biofilter type differed among systems, and included upflow pulsed bed bead filter, packed tower trickling filter, and rotating biological contactor. Following filter acclimation, a comparative analysis of biofilter performance was conducted, involving measurement of temperature, pH, dissolved oxygen, total ammonia-nitrogen, nitritenitrogen, nitrate-nitrogen, alkalinity, total hardness, carbonaceous biochemical oxygen demand, dissolved organic carbon, and total suspended solids. Filter bed emergence promoted effective carbon dioxide stripping, pH maintenance, and consistent nitrification performance in trickling filters and rotating biological contactors. Higher total ammonia nitrogen mass removal rates were observed in trickling and rotating biological contactor filters than in bead filters. Low total ammonia nitrogen mass removal rates and nitrification efficiencies for all filters resulted from relatively high carbonaceous biological oxygen demand loadings. Analysis of areas under mass removal curves showed that RBC filters were surface area limited. Foam formation in trickling filters effectively removed total suspended solids from the culture water. Filter type did not have a significant effect on median organic water quality parameter values in the production tanks. Although differences in nitrification performance and certain water quality parameters were observed between filter types, the data set did not indicate that one filter type should be considered generally most effective at treating wastewater produced in a recirculating aquaculture system.
Evaluation of Dissolved Chitosan for Suspended Solids Removal
Tsukuda, S.; Davidson, J.; Adkins, E.; Summerfelt, S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
In a preliminary study conducted at The Conservation Fund Freshwater Institute (Shepherdstown, WV, USA), dissolved chitosan was added to a recirculating system to determine if the chitosan would coagulate particulate matter and consequently increase solids removal. The recirculating water became visibly clearer and the culture tank total suspended solids (TSS) concentration dropped from 10.7 to 2.9 mg/L within 2 hours after dosing had been initiated. However, fish showed symptoms of distress and the chitosan treatment was discontinued. In subsequent studies conducted to determine the particle capture mechanism associated with chitosan addition, effluent treated with dissolved chitosan was not returned to the system. The results of two jar test studies indicated that dissolved chitosan did not enhance particle capture by settling or by microscreen filtration when mixed with a fish culture system effluent containing * 10 mg/L of TSS. However, these jar tests indicated that an additional 44% of TSS could be removed from the water that had already passed through a microscreen filter if this water was treated by a mixing and settling step, even without addition of dissolved chitosan. Additional studies using small-scale fluidized-sand biofilters indicated that the reduction in TSS observed in our initial experiment was due to TSS capture in the fluidized sand biofilter. TSS concentrations were reduced from 5.1-7.4 mg/L at the biofilter inlet to 1.7-2.2 Ihg/L at the biofilter outlet. Thus, adding dissolved chitosan to water flowing into a fluidized-sand biofilter turned the biofilter into a novel type of upflow 'sludge blanket clarifier,' which appears to be both non-plugging and relatively simple to operate. In addition, dissolved chitosan did not change nitrification occurring within the fluidized-sand biofilter. Therefore, adding a coagulant (such as dissolved chitosan or a non-toxic polymer) to the flow entering a fluidized sand biofilter has the potential to create a unit process that reduces TSS while simultaneously treating dissolved wastes.
Estimating Metabolism of Fish in Aquacultural Production Systems
Neill, W. H.; Oborny, E. L. Jr.; Craig, Steven R.; Matlock, M. D.; Gatlin, D. M. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
Open-system respirometry offers a practical approach for measuring metabolic rates of fish cultured at high densities in uncovered raceways. Central to this methodology is analysis of a dynamic mass-balance on oxygen supply and demand. Here, we present a validated mass-balance equation, describe minimally disruptive procedures for estimating its parameters, and illustrate its use in estimating the oxygen-uptake rate of fish as a group, in real time and under actual production conditions.
Organoleptic, Chemical and Microbiological Changes in European Eel (Anguilla anguilla L.) During Storage: Skinned vs. Unskinned Fish held at 2C and 5C
Mclean, E.; Ronsholdt, B.; Roesen Norgaard, R.; Kjolby Jensen, C.; Jacobsen, L. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
Studies were undertaken to examine quality deterioration in stored skinned and unskinned fresh eels derived from a commercial recirculation facility. Fish samples were held at 2 and 5T for 18 days and examined sensorially, chemically and microbiologically. Oil content of experimental animals averaged 39.1%, that for dry matter was 47.8% and 12.1% and 0.69% for protein and ash content respectively. Trimethylamine-oxide (TMA-0) and trimethylamine (TMA) levels remained below detection limits(< 0.7 mg N 100 g-1 throughout the study. Shelf life was extended for both skinned and unskinned fish at the lowest temperature. By day 14 of the trial, differences (P < 0.05) were detected by sensorial evaluation for both temperatures evaluated and between skinned and unskinned animals. Increases (P < 0.05) were detected for TVB-N throughout storage with fish held at 5°C expressing higher levels (P < 0.05). Sample lipid oxidation increased throughout the study period. TBA was determined as a suitable variable for predicting overall impression of product quality. K1 value illustrated significant (P < 0.0001; R2 0.72) polynomial correlation with overall impression.

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