Influence of co-feeding larvae with live and inert diets on weaning the sole Solea senegalensis onto commercial dry feeds

The senegal sole (Solea senegalensis) is a potential culture species in sal t water ponds in south Spain and Portugal. However, growth of an industry a round this species is constrained by poor survival during weaning from live Artemia onto artificial diets. This paper describes the influence of larva l conditioning with inert diets on weaning performance. Mixed diets of comm ercial formulated feed and live prey (rotifers and Artemia) allowed larvae to develop from first feeding to metamorphosis without significant differen ces (P>0.05) in specific growth rate (SGR) (18.8% +/- 1.2 and 18.1% +/- 2.2 ) and survival (61.5% +/- 10.6 and 61.1% +/- 9.4) compared to larvae fed li ve feed alone (SGR of 18.4% +/- 1.1 and survival of 71.6% +/- 25.9). In met amorphosed fish, however, significant differences (P < 0.05) in survival af ter weaning onto commercial feeds occurred after 50 days of culture, accord ing to previous co-feeding with live and inert feeds during the larval stag es. There was no growth or survival in fish weaned without any previous lar val co-feeding. Metamorphosed fish previously fed a 1:1 ratio of live-inert feed during larval stages, had a similar SGR (5.1% +/- 0.1, P > 0.05) afte r weaning (day 70) to that obtained for fish that remained all the time on Artemia (5.3% +/- 0.1). The SGR after weaning significantly decreased (3.4% +/- 0.3, P < 0.05) when the larval co-feeding regime had a higher proporti on (2:1) of live feed. Survival for the weaning period was significantly lo wer (P<0.05) in weaned fish (39.0% +/- 4.2 and 34.0% +/- 11.3 for 2:1 and 1 :I live:inert larval co-feeding) compared to fish that remained on live fee d (78.5% +/- 5.0). This study demonstrates the feasibility of early weaning of S. senegalensis and that larval co-feeding enhances growth and survival after weaning. (C) 1999 Elsevier Science B.V. All. rights reserved.