Diet composition and feeding habits of fish larvae of two co-occurring species (Pisces: Callionymidae and Bothidae) in the North-western Mediterranean

Larval diet and feeding habits of the marine fish Callionymus sp. and Arnoglossus laterna larvae, two species co-occurring in the Catalan Sea (May, 1992), were compared. For the Callionymus sp. larvae, the dominant prey were Oithona spp. and Oncaea sp. copepodites, and with less frequency, Paracalanus sp. copepodites. For A. laterna larvae, the diet was composed only of Paracalanus sp. copepodites. Copepod nauplii were not important in the diet of these two species, although they were the most abundant zooplankter in the area. As larvae of both species grew, the size and number of prey increased. This tendency was more obvious in Callionymus sp. larvae, which reflected a greater prey diversity during all their early ontogeny. An analysis of covariance showed prey size increased with larval size in both species, but the prey consumed by Callionymus sp. larvae was larger than prey of A. laterna, corresponding to the larger mouth size (p<0.001). The results of this study show that these co-occurring species have different feeding strategies.