Spongivory by juvenile angelfish (Pomacanthidae) in Salvador, Bahia State, Brazil

Adult angelfish of the genera Pomacanthus and Holacanthus (Family Pomacanthidae) are considered the most important spongivorous fishes of the Caribbean, with sponges comprising more than 70% of their gut contents. However, despite their commercial importance as ornamental fish, little is known about the diet of juvenile angelfish, which are generally considered to be cleaners. The goal of this study was to identify through gut content analysis the sponge species eaten by juveniles of the angelfish Pomacanthus paru, Holacanthus ciliaris and Holacanthus tricolor in Salvador, Bahia state, Brazil. We also estimated the frequency of occurrence of each sponge species in the diet of juvenile angelfish, and tested the correlation between fish size and number of sponge species preyed. In Salvador, 34 species of sponges were found in the gut contents of 14 out of 16 specimens of juvenile angelfish. Twenty-two species of sponges were eaten by Holacanthus tricolor, 15 by H. ciliaris, and 14 by Pomacanthus paru. There was a significant positive correlation between fish size and number of preyed sponge species, but the coefficient of determination was low and even the smallest fishes had sponges in their gut contents. These findings indicate that juveniles of all three species of angelfish are generalists in the consumption of sponges in Brazil, a diet similar to that of the adults. The most frequent sponges in juvenile angelfish gut contents were Tedania ignis, Mycale sp., and Spirastrella sp., all with 37.5% of frequency in the 16 stomachs analyzed. Tedania ignis was not consumed by H. ciliaris in Salvador, but it was consumed by the other fish species, being the most frequent prey of H. tricolor and P. paru. Juvenile angelfish probably adapt to a cleaning behavior or to benthic feeding according to local environmental conditions. The development of sponge-based artificial foods may allow longer maintenance and reproduction of angelfish in aquaria, thus helping to protect their natural populations.