Biofloc technology application in African catfish fingerling production: The effects on the reproductive performance of broodstock and the quality of eggs and larvae

The present study evaluated the effects of biofloc technology (BFT) application on African catfish (Clarias gariepinus) fingerling production with more focus given to the reproductive performance of broodstock and the quality of eggs and larvae. For broodstock experiment, two broodstock culture systems were compared, i.e. biofloc and control systems. In biofloc systems, regular additions of organic carbon source (molasses, C/N ratio of 10) were conducted to stimulate the growth of heterotrophic microbial biomass as the main constituent of biofloc, whereas no molasses was added to the control systems. Young female broodstock with a mean body weight of 657 +/- 0 g were maintained in three replicate outdoor tanks (2.5 x 2.0 x 0.8 m) per treatment at a density of 5 fish/m(2), whereas male fish were maintained in two replicate tanks per treatment at a density of 4 fish/m(2). The larvae produced by the broodstocks in both systems were subsequently assessed by larval starvation tolerance test and growth test. The gonadosomatic index (GSI) and fecundity of female broodstocks in both treatments were generally comparable, except on day-122 when the relative fecundity of biofloc broodstock was 26% higher than that of the control (P < 0.05). Interestingly, the embryonic development rate of eggs produced by biofloc broodstocks was higher than that of the control (P < 0.05). The survival in starvation tolerance test and growth tests was notably improved in the larvae produced by biofloc broodstocks. Further more maintaining the larvae in biofloc systems could also enhance the fish survival and final body length. Statement of relevance: This study demonstrates a novel research on the application of biofloc technology in broodstock and larval rearing of African catfish. Housing African catfish broodstock in biofloc systems significantly affected the embryonic development rate and the larval quality. Improvements in survival and growth were observed in the larvae housed in biofloc systems. (C) 2016 Elsevier B.V. All rights reserved.