Introduction Pond culture is the standard method of producing tilapia in the tropics. Pond culture depends on phytoplankton to generate oxygen and absorb dissolved nitrogenous waste. The feeding rate limit for fed ponds is determined by the ability of the pond’s microbial community to assimilate fish waste products such as ammonia and solid waste, which undergoes microbial decomposition. The feeding rate limit determines a pond’s production capacity. A standard production level for a fed pond is 5,000 kg/ha. The production level can be increased with aeration and/or water exchange.
An intensive biofloc system was developed at the University of the Virgin Islands, which reduces the limitations of pond culture (Rakocy et al. 2000; Rakocy et al. 2002, Rakocy et al. 2004). The biofloc tank was continuously aerated and did not depend on phytoplankton for oxygen production. The primary component of the microbial community was shifted from phytoplankton to chemoautotrophic bacteria, which removed ammonia and nitrite. Settleable solid waste was removed daily through a sedimentation process. The culture water was mixed to suspend the microbial community and maximize contact between bacteria and waste products. The culture water contained high concentrations of phytoplankton, but the phytoplankton community did not play as dominant a role in maintaining water quality as in pond culture. As four production trials were conducted, the system was modified to enhance performance and maximize production.