First feeding parameters of the milletseed butterflyfish Chaetodon miliaris

摘要

First feeding performance of the milletseed butterflyfish (Chaetodon miliaris) was evaluated using three experiments examining prey type, microalgal cell density and prey density. To ensure no size bias existed between trials, morphometric measurements, fertilization and hatch rates were recorded for each trial. The proportion of larvae feeding and feeding intensity were measured in each experiment. To evaluate prey type, larvae were offered small size Brachionus plicatilis and Parvocalanus crassirostris nauplii in clear water and water greened with Tisochrysis lutea (Tiso). In trial 1, green water and P.crassirostris nauplii had a significantly higher proportion of larvae feeding and feeding intensity. In trial 2 no differences were detected between P. crassirostris treatments. Microalgae experiments evaluated six treatments ranging from 0 cells/ml to 8 x 10(5) cells/ml. Feeding response increased as microalgae was added to the environment, but no statistical differences were discerned between treatments besides the highest cell density (8 x 10(5) cells/ml) and lowest cell density in both trials (0 cells/ml). To determine if prey density had an effect on first feeding response P.crassirostris nauplii were added to tanks at 1 to 15 nauplii/ml. No significant differences in the feeding response were found between prey densities of 1-15 P.crassirostris nauplii/ml in either trial. This study revealed that C. miliaris larvae had the highest first feeding response, measured by the proportion of larvae feeding and feeding intensity per larvae, with the prey item P.crassirostris nauplii in green water and prey densities between 1 and 15 nauplii/ml.