Feed preference of milkfish ( Chanos chanos Forsskal) fry given different algal species as natural feed

Abstract

Acclimated milkfish fry (mean wet weight, 6.0 mg) were fed with unialgal cultures of five species of freshwater algae: Oscillatoria quadripunctulata, Chroococcus dispersus, Navicula notha, Euglena elongata and Chlorella ellipsoidea. In the first experiment, the filamentous blue-green alga, Oscillatoria, appeared most acceptable to milkfish fry throughout the growing period, while feeding milkfish fry with the unicellular species, Chroococcus, resulted in lower weights and survival. In the second experiment, increases in weight of milkfish fry fed with Oscillatoria alone or in combination with Chroococcus were comparable. However, a significant increase in survival was obtained with the combination feeding. A third experiment showed that high density cultures of Oscillatoria resulted in significantly large weight increments in all growth stages. The other algae tested did not support growth of milkfish fry. 14C-Labeled algae of the same species were fed to milkfish fry. Significantly high assimilation retes were observed in almost all growth stages of milkfish fry with Oscillatoria alone or Chroococcus alone. Negligible amounts of Navicula, Chlorella and Euglena were assimilated.