The eect of vitamins C and E in (n-3) highly unsaturated fatty acids-enriched Artemia nauplii on growth, survival, and stress resistance of fresh water walleye Stizostedion vitreum larvae S. KOLKOVSKI 1 , S. CZESNY 1 , C. YACKEY 1 , R. MOREAU 1 , F. CIHLA 2 , D. MAHAN 2 & K. DABROWSKI 1 1 School of Natural Resources and 2 Department of Animal Sciences, The Ohio State University, Coey Road Columbus, USA Abstract This study aimed to evaluate the eect of enriching Artemia nauplii with vitamin C (ascorbyl-6 palmitate) or vitamin E (a-tocopherol acetate), 20% w/w, together with a mixture of concentrated eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) on the growth, survival, and stress resistance of fresh water walleye Stizoste- dion vitreum larvae. Either cod liver oil (CLO) or EPA/DHA ethyl esters concentrate was used as lipid sources in the Artemia enrichment. Walleye larvae were fed ad libitum for 40 days. At day 40, submersion in salt water (25 g L )1 1 ) was performed to evaluate larvae resistance to stress. EPA and DHA levels in walleye juveniles fed EPA/DHA-enriched Artemia increased signi®cantly, by an average of 650% compared with ®sh fed non-enriched Artemia. A signi®cant increase was found for vitamins C (71.8  1.0 and 42.7  1.2 lgg )1 wet weight (WW) 2 ) and E (17.0  3.7 and 6.5  0.9 lgg )1 WW) concentrations in ®sh fed en- riched and unenriched Artemia, respectively. Growth was comparable throughout treatments, whereas survival was signi®cantly higher in ®sh fed CLO-enriched Artemia nauplii compared with ®sh fed Artemia nauplii enriched with EPA/ DHA concentrate. The addition of vitamin C increased ®sh survival by 1.4-fold compared with ®sh fed Artemia enriched with only EPA/DHA concentrate. The survival of the latter was similar to control ®sh (Artemia without enrichment). The supplementation of vitamin E did not aect ®sh survival signi®cantly. Stress tests revealed that the resistance of walleye larvae to salinity changes increased when Artemia enrichment was supplemented with vitamin C. However, walleye larvae fed CLO-enriched Artemia had the best performances in the stress test. KEY WORDS: KEY WORDS: Artemia, enrichment, n-3 HUFA, vitamin C, vitamin E, walleye Received 2 November 1998, accepted 9 February 1999 Correspondence: K. Dabrowski, School of Natural Resources, The Ohio State University, 2021 Coey Road, Columbus, OH 43210, USA. E-mail: dabrowski.1@osu.edu Introduction The use of Artemia nauplii as live food for crustacean and ®sh larvae is widespread in marine and freshwater aquacul- ture. Artemia nauplii can be oered either solely or enriched with essential nutrients. These enrichments provide high levels of phospholipids containing highly unsaturated fatty acids, especially highly unsaturated fatty acid (HUFA), eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) (LeÂger et al. 1985; Koven et al. 1993). In most marine ®sh larvae, Artemia nauplii-enrichment is commonly used since it enhances growth and survival (Sorgeloos et al. 1998). Vitamin C (ascorbic acid) is considered to be an essential component in diets for teleost ®sh. Fish larvae are particularly sensitive to vitamin C de®ciency (Dabrowski et al. 1996). Their rapid growth rate suggests that larvae have higher vitamin requirements than juveniles and adults. Addition of vitamin C to larval diets improved survival, growth perfor- mance, skeleton development, stress resistance and immune response (Merchie et al. 1996). Although ascorbyl acid 2-sulphate (stable derivative of ascorbic acid) was found in Artemia cysts and nauplii (Mead & Finamore 1969; Dabrow- ski 1991; Merchie et al. 1995a), the amount of the free form 199 Aquaculture Nutrition 2000 6 ; 199^206 .............................................................................................. .............................................................................................. Ó 2000 Blackwell Science Ltd