Title: Solids management in a channel catfish biofloc technology production system Author
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: December 4, 2013
Publication Date: N/A
Technical Abstract: Biofloc technology (BFT) production systems are being used more commonly to produce high yields of fish or shrimp because very high feed rates are possible. In an outdoor BFT production system, a complex of living organisms is closely associated with particulate organic matter and is maintained in suspension by continuous aeration. Ammonia excreted by the culture animal is utilized by the phytoplankton and bacteria that are part of this complex of living organisms. Concentrations of total suspended and settleable solids can reach levels that impact culture animal performance. The objective of this study was to evaluate the effect on net yield and water quality of three solids management protocols using a completely randomized experimental design. Fingerling catfish (49.2 g/fish) were stocked into nine continuously aerated HDPE-lined tanks (18.6 m2, 15.5 m3) at 0.7 kg/m3 (12.1 fish/m2). Each tank was equipped with a 117-L conical bottom settling chamber. Flow rates tested were 0, 0.6 and 2.5 L/min (hydraulic residence time for the two exchange rates was 17.0 and 4.3 d, respectively). Water was moved from the tank to the settling chamber by airlift pump; flow rate was controlled by air injection depth. Fish were fed daily to apparent satiation with a 32% protein floating extruded feed. Dissolved oxygen and temperature were measured continuously using sensors connected to a data logger. Water quality variables (pH, TAN, NO2N, NO3N, SRP, total alkalinity, settleable solids, total suspended solids, total volatile solids, and chlorophyll a) were measured on a weekly basis. Relationships between solids management regime and net yield or water quality variables will be presented.