Successful culture of marine fish is reliant on feeding live feed organisms to small larvae to maximize survival. Currently most larvae are cultured by feeding live rotifers and Artemia nauplii and occasionally copepod nauplii. Larvae consume various zooplankton in the wild, including copepod nauplii, ciliates, and less commonly rotifers. Research was conducted to define live food preferences during the early larval stages of three marine fish larvae.
This study used different colored fluorescent microspheres (1-2 µm diameter) to mark different prey organisms and then fed them to larvae at specific densities. Larvae were yellow domino damselfish at 1 and 3 days post hatch (dph), spinecheek clownfish at 0 dph, and pigfish larvae at 3 dph. Rotifers (Brachionus rotundiformis), copepod (Parvocalanus crassirostris) nauplii, and the ciliate (Euplotes sp.) were each marked with different colored fluorescent microspheres (Figure 1) and fed in different combinations to larval fish. Larvae were preserved and placed under a fluorescent microscope which clearly identified the prey organisms consumed.
Results indicated that rotifers were the least preferred by all species, while copepod nauplii were favored by most larvae, confirming their importance as a primary feed organism. Ciliates, a novel live food organism not commonly used in aquaculture, were consumed by all larvae, highlighting their potential as a valuable prey organism especially for small larvae that cannot consume larger prey due to their small mouth gapes. Variations in prey preferences by species at different developmental stages justifies further research to investigate feeding novel prey types at different developmental stages and to define shifts in prey preference as larvae grow.