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In this study Atlantic halibut (Hippoglossus hippoglossus L.) larvae (0.12 + 0.04 g) were, from day 40 post first feeding, offered six diets in which 10% or 30% of the dietary protein was hydrolysed with (a) pepsin (P), (b) pepsin trypsin (PT) or (c) pepsin trypsin chymotrypsin (PTC). In addition, a diet without hydrolysed protein was offered, and enriched Artemia was fed as control. The amount of soluble protein increased progressively with the enzyme treatments P, PT and PTC and with higher inclusion levels of hydrolysed protein. Survival was highest among the larvae offered Artemia (83 + 0%) or the diet 10P (10% pepsin hydrolysed protein; 67 + 4%). The diet 10P supported survival significantly better than the more hydrolysed diets 10PTC, 30P, 30PT and 30PTC, but not significantly better than the non-hydrolysed diet and 10PT. Specific growth rate (SGR) was 1.76 + 0.20 in average for all groups of larvae and was not significantly affected by the diets. Still, the larvae offered pepsin hydrolysed diets tended to have better growth (2.10 + 0.05 SGR; P <0.06) than the larvae offered the other hydrolysed diets. The larvae offered the formulated diets did not differ in chemical composition. Ã 0-diet: non-hydrolysed diet; 10P, and 30P: 10% and 30%, respectively, of the dietary protein was hydrolysed with pepsin; 10PT and 30PT:10% and 30%, respectively, of the dietary protein was hydrolysed with pepsin and trypsin; 10PTC and 30PTC: 10% and 30%, respectively, of the dietary protein was hydrolysed with pepsin, trypsin and chymotrypsin. ²Fish meal extract. See Material and methods and Sola et al. except for a-tocopheryl absorbate supplemented at 200 and ascorbyl palmitate at 400 mg kg À1 . Aquaculture Research, 2002, 33, 311±321 Atlantic halibut larvae fed predigested protein A Kva Êle et al.

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Bergh, IZI., K.E. Naas, and T. Harboe. 1994. Shift in the intestinal microflora of Atlantic halibut (Hippoglossus hippoglossus) larvae during first feeding. Can. J. Fish. Aquat. Sci. 51 : 1899-1 903.Isolates of aerobic intestinal bacterial flora from unfed Atlantic halibut (Hippoglossus hippoglossus) larvae revealed a population dominated by nonfermentative rods of the Cytophag~Flexibacter/Flavobacteriurn group. Following the onset of feeding, the flora gradually changed towards a fermentative flora dominated by the Vibrio/Aeromowas group. This transition occurred faster in a group which was reared in water containing cultivated phytoplankton, in contrast with groups where the larvae were kept in filtered water. No major differences in the bacterial fiora of the tank water were found among the groups.Des isolats de flore intestinale aerobie provenant de iarves de fletan atlantique (Hippoglossus hippoglossus) non alirnentees ont revkle une population dorninee par des batonnets non ferrnentatifs appartenant au groupe Cytsphag~Flexibacter/F~avobacteriurn. AprPs le d&but de Ifalimentation, la flore s'est graduellement rnodifiee pour devenir une flore fermentative dominee par le groupe Vibrio/Aerornonas. Cette transition s'est produite plus rapidement chez un groupe qui a 6t6 kleve dans de I'eau renfermant du phytopiancton cultive, contrairement aux groupes dcsnt les larves csnt ete gardees dans de Ifeau filtree. On n'a observe aucune difference importante dans la flore bacterienne presente dans I'eau des bassins renfermant les divers grsupes.