Biological evaluation of three phytoplankton species (Chlorella sp., Tetraselmis sp., Isochrysis galbana) and two zooplankton species (Crassostrea iredalei, Brachionus plicatilis) as food for the first-feeding Siganus guttatus larvae

Abstract

First-feeding Siganus guttatus larvae were given different species of phytoplankton (Chlorella, Tetraselmis, Isochrysis) and zooplankton (oyster trochophores, Brachionus) or a combination of both on the first day when they can feed. None of the phytoplankton species when used as the only food source for the larvae could support life beyond four days from hatching. Brachionus of sizes less than 90 microns was the most suitable food for the first-feeding larvae. A food mixture of the three phytoplankton species and Brachionus resulted in survival rates that were significantly higher than with other treatments. Larval growth, however, did not differ significantly (p>0.05).

Different Brachionus densities were also used during the first-feeding days. Although the range of 10 to 15 Brachionus per ml gave better survival, no significant difference existed. Growth was slightly greater but not significantly different at higher densities.