The size of protozoa is smaller than rotifer and copepod nauplii could be suitable as first feeding food sources for the smaller mouth of marine fish larvae. The object of this study is to develop a cultural technique of the small protozoa.
Small ciliate, Euplotes sp., which size is about 30 µm was isolated from the culture pond outdoors and culture in the laboratory. An experiment was conducted to understand the optimal feeding concentrations for this species. Put 5 g artificial prawn food powder into beaker with 100 ml reverse osmosis water as the food sources for this experiment. Seven feeding levels of adding 0, 1, 2,3,4,5 and 7 ml from above culture medium were performed in this experiment. Each treatment has three replicates. The initial density of Euplotes sp. was 120 cells/ml. Results showed that the concentrations of adding 3 ml treatment was obtained the maximum density 2800 cells/ml after 72 hours.
To determine the effect on the survival of marine fish larvae (surgeonfishes, Paracanthurus hepatus ) for feeding the protozoa, Euplotes sp. at 0, 5,10 and 15 densities. Results showed that the survival was better than control at 5, 10 and 15 densities at the fifth day (after hatching), but no significant difference among three treatments. The optimal density of Euplotes sp. was 5 cells/ml in this experiment.