Feeding behaviour of greenback flounder larvae, Rhombosolea tapirina (Gunther) with differing exposure histories to live prey

This study examined the feeding performance of cultured larvae of the greenback flounder Rhombosolea tapirina, using the live feed organisms, Brachionus plicatilis and Artemia sp., to determine the primary sensory modality involved in feeding, and the effect of previous exposure to prey on subsequent prey selection. The proportion of larvae that fed on rotifers in the light (400-700 nm daylight fluorescent tubes - light intensity of 5-6 μmol s-1 m-2), increased significantly from 66% to 96% from day 12 to day 27 post-hatching, respectively. In comparison, the proportion of larvae that fed on rotifers in total darkness, never exceeded 5% during the same period. This indicates that greenback flounder larvae are primarily dependent upon vision to feed. Prior feeding experience of greenback flounder larvae with either rotifers only (R-treatment) or a mixed diet of Artemia and rotifers (A and R-treatment) significantly affected subsequent prey selection when larvae were offered a mixed diet of Artemia and rotifers. It did not, however, affect the temporal onset of selection of the novel prey species (Artemia) by R-treatment larvae. Therefore, the differences in prey selection by larvae, with or without prior exposure to Artemia prey, were not due to the inability of larvae to handle and ingest a novel prey species, but they reflect positive selection for familiar prey. The latter indicates a learned component in the feeding behaviour of fish larvae. This has implications for the timing of the introduction of new live prey species during intensive culture of marine fish larvae. (C) 2000 Elsevier Science B.V.