Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/2011
Publication Date: 2/29/2012
Citation: Green, B.W. 2012. Destiny-yield relationship for channel catfish reared in a biofloc technology production system [abstract]. Book of Abstracts Aquaculture America 2012: Bringing all the Players to the Table. p.206.
Technical Abstract: The effect of stocking density on yield of stocker channel catfish and water quality in a biofloc technology production system was studied in this completely randomized design experiment. Fingerling channel catfish (Ictalurus punctatus; 48.0 g/fish, 17.8 cm/fish) were stocked into nine continuously aerated HDPE-lined tanks (18.6 m2, 15.5 m3) at 26, 35, or 44 fish/m2 (1.4, 1.8, or 2.3 kg/m3) in mid-April. Three tanks were stocked with each stocking rate. Water was added to tanks only to replace evaporative losses. Fish in each trial 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. Fish were harvested after 183 d. Feed consumption by fish increased with increasing water temperature. Mean daily feed rate averaged 86.9, 104.6, or 132.1 g/m3 during the peak feeding period (7 July-27 September). Stocker catfish at harvest averaged 173, 140, or 145 g/fish for the1.4, 1.8, or 2.3 kg/m3 treatments, respectively. Corresponding net yields were 3.5, 3.3, or 4.6 kg/m3, respectively. Phytoplankton biomass, as indicated by chlorophyll a, increased rapidly after tanks were stocked and remained high throughout the study. Nitrification, as indicated by increasing NO3N, began early in June. After an initial spike (2-3 mg/L TAN) following stocking, ammonia concentration remained low (< 0.1 mg/L) despite increasing daily feed rates because of uptake by phytoplankton and nitrification. Settleable solids, total suspended solids (TSS) and total volatile solids increased with increasing feed rate. Maximum TSS concentration was 2,100 mg/L. Daily feed consumption did not continue to increase with fish growth once TSS exceeded 560-830 mg/L at water temperatures above 25 C.