High density large-scale culture of Moina macrocopa by improvement of aeration equipment

The freshwater cladocera Moina macrocopa is a major live food in the propagation of early stage of freshwater fish species. As little research has been conducted to establish an effective culture technique, productivity of M. macrocopa culture remains unstable. Based on the observation of biological characteristics of M. macrocopa, we examined the conditions to develop large-scale culture system using 0.5-1.0 cubic m small-scale circular tanks. The goals we aimed at were: 1) to disperse M. macrocopa homogeneously in the culture tank, 2) to prevent damage of M. macrocopa caused by direct exposure to aeration, 3) to control water movement below swimming speed (about 3 cm/sec) of M. macrocopa, 4) to supply enough oxygen to the culture water. In 3 days culture experiment at 28 deg C using 0.5 cubic m culture tanks, we could harvest at 2.85 kg and 2.90 kg (wet weight) M. macrocopa using triple and quadruple piped aeration equipments, respectively. Under the same condition in 1.0 cubic m tanks, we harvested 7.65 kg M. macrocopa using quadruple piped aeration equipment. The feed conversion fed concentrated freshwater Chlorella was 0.87-0.89g (M. macrocopa)/ml (Chlorella) in 0.5 cubic m tanks and 1.10 g/ml in 1.0 cubic m tank. These results suggest that high density large-scale culture of M. macrocopa is possible using these equipments, and that it is possible to harvest M. macrocopa daily throughout the year by setting 3 large-scale culture tanks in a system.