Fatty acid composition, growth and morphological deformities in juvenile cyprinid, Scardinius erythrophthalmus fed formulated diet supplemented with natural food Ewa Kamler ⁎, Jacek Wolnicki, Rafał Kamiński, Justyna Sikorska The Stanisław Sakowicz Inland Fisheries Institute, Pond Fishery Department, Żabieniec, 05-500 Piaseczno, Poland ABSTRACT ARTICLE INFO Article history: Received 8 August 2007 Received in revised form 10 March 2008 Accepted 11 March 2008 Keywords: Body deformities Chironomid larvae Dry diet supplementation Growth Fatty acids Scardinius erythrophthalmus Response of a freshwater cyprinid fish Scardinius erythrophthalmus juveniles (initial age 195 days, initial weight 0.82 ± 0.06 g) to supplementation of a formulated commercial dry diet with natural food was examined. A 90-day experiment at 25 °C consisted of two periods. During 60 days three feeding groups were studied: the group F received the dry diet Futura exclusively, the group FC was fed Futura supplemented with frozen larvae of Chironomidae, and the group C received exclusively chironomids. This was followed by a 30 days “recovery period” during which all fish received larval chironomids, only. No mortality occurred during the experiment. The poorest growth was found in the F group, in the supplemented group FC growth was intermediary, and the best growth took place in the C group. The highest condition coefficient was in the group F, the lowest one in the group C. In the group F incidence of spinal curvatures was the highest (77.8% on day 60), in the group FC it was intermediary (42.2%) while no body deformities were found in the group C. After a month exclusively on chironomids (day 90) percentage of deformed fish declined to 66.3 and 31.3, respectively, for the groups F and FC. The proportions of fatty acids in Futura were typical of a formulated diet based on n-3 rich oils: a high concentration of n-3 PUFA (26.9% of total fatty acids, predominantly docosahexaenoic acid DHA, C22:6n-3), and a low concentration of n-6 PUFA (4.9%). In contrast, chironomids contained only 5.9% n-3 PUFA, and a high concentration of n-6 PUFA (28.8%, mainly linoleic acid LA, C18:2n -6 and arachidonic acid AA, C20:4n-6), which compares well with natural food of freshwater fish. Fatty acid composition of fish whole body lipids reflected the fatty acid profiles of the respective diets, while chironomid supplementation to Futura resulted in intermediary values. Diet-induced change in the fatty acid profiles seems to be a relatively slow process. Supplementation of formulated dry diets deficient in n-6 fatty acids with natural invertebrate food could be regarded as a technique to mitigate body deformities in freshwater fish juveniles. We suggest that the diets manufactured for freshwater juveniles should resemble their natural invertebrate prey. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Fatty acids play a major role as an energy source, affect cellular membrane structure and functions, are important for cell growth, differentiation and metabolism, improve resistance to stress (starva- tion or osmotic shock), and regulate gene expression (Kestemont et al., 1996; Jump and Clarke, 1999; Sargent et al., 1999; Cahu et al., 2003; Tocher, 2003; Xu et al., 2003; Villeneuve et al., 2005). It is well established that dietary concentrations of fatty acids determine their concentrations in the body (examples for juvenile freshwater fish in Guillou et al., 1995; Ahlgren et al., 1999; Martino et al., 2002; data for Salmo salar in Schlechtriem et al., 2007; review by Steffens and Wirth, 2005). Some evidence exists indicating teratogenic effects of inappropriate dietary fatty acid composition in fish juveniles (Ahlgren et al., 1999; Bell et al., 1999; Gapasin and Duray, 2001). However, no data are currently available on the body fatty acid profile formation under a feeding regime involving natural food supplemented to formulated diets. Supplementation of natural food (frozen chironomid larvae) to a dry diet was shown to improve growth in cyprinid juveniles (Wolnicki et al., 2003; Wolnicki, 2005). Questions arise: could this technique be effective in mitigation the incidence of body malformations? Could fatty acid composition of aquatic invertebrates be suggested to follow in formulation of diets for freshwater juvenile fish, similarly as fatty acid composition in diets manufactured for marine fish larvae were based on that in their natural nutrient sources: fish eggs and marine zooplankton (Sargent et al., 1999)? Skeletal malformations are an important bottleneck in larval and juvenile fish culture (Cahu et al., 2003; Kolkovski and Sakakura, 2004; Villeneuve et al., 2005; Zambonino et al., 2005). Body deformities are a major problem in rearing of cyprinid juveniles on dry formulated diets, for example Chondrostoma nasus (Wolnicki and Myszkowski, Aquaculture 278 (2008) 69–76 ⁎ Corresponding author. Tel.: +48 22 7562044; fax: +48 22 7562088. E-mail address: Kamler@infish.com.pl (E. Kamler). 0044-8486/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2008.03.012 Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aqua-online