CATFISH PRODUTION IN FLOATING RACEWAYS

Fernando Kubitza*, Jesse Chappell and Terry R. Hanson
School of Fisheries, Aquaculture and Aquatic Science, Auburn University (SFAAS-AU)
203 Swingle Hall, Auburn, AL, USA 36849; e-mail: fzk0006@auburn.edu  

In 2016, a four-year study was initiated to establish production protocols, safe standing crop levels and economic feasibility analyses for culturing hybrid catfish in In-Pond Raceway Systems (IPRS). One floating IPRS was placed in each of the four 0.4-ha ponds used in the study. Two IPRS' have a fish growing volume of 64 m3 (4.9 m wide, 10.7 m long and 1.22 m deep) and two have 45 m3 (3.05 m wide, 12.20 m long and 1.22 m deep). Sides and bottom of IPRS were made with 3-mm HDPE liner and the inlet and outlet screens used to enclose the fish were made of 1/2" x 1" PVC coated steel mesh wire. Each IPRS has an air-lift water moving device (a grid made with 12 m of diffuser hose placed under a directional hood) positioned just before the inlet screen. A 1.5 HP air blower propels each water moving device, supplying a constant water flow through the IPRS unit and providing supplemental aeration to increase the oxygen levels within the IPRS during night and early morning hours. IPRS units are covered with a 25 mm net to prevent bird predation.  

The first year of this project was aimed at assessing whether a commercial size catfish (680 g up) could be produced in one growing season and if ponds fitted with IPRS units could yield a fish biomass twice as much as the fish yield attained in conventional catfish ponds (7,800 kg/ha/yr). Hybrid catfish juveniles (mean wt 41 g) were stocked into the IPRS units in March 2016 and fed 32% CP commercial catfish pellets once or twice a day, according to water temperature and dissolved oxygen conditions. Feed allowance was adjusted every two weeks, by estimating how much feed fish were able to eat in an "up to five minutes" period. Fish were sampled at monthly intervals to estimate average weight, specific daily growth and FCR. Raceways were inspected daily for the presence and removal of dead fish. Results are summarized in Table 1. A sequence of bacterial infections in the second month of the study (first Flavobacterium columnare, second Edwardsiella ictaluri) caused significant losses of fish in all raceways, especially in B1, B2 and B4. Fortunately, fish were still small at the onset of those infections, causing minor losses of biomass. FCR ranged from 1.52 to 1.75. Final standing crop nearly equaled or surpassed mean catfish yield in conventional ponds and mean weight of fish ranged from 670 to 820 g. Estimated production costs ranged from US$ 2.01 to 2.35/kg of fish. More information on IPRS and economic data on this trial will be presented at WAS Conference.