Survival, growth and condition of tench Tinca tinca (L.) larvae fed live food for 12, 18 or 24 h a day under controlled conditions

The present 20-day trial was performed in order to improve growth of tench Tinca tinca (L.) larvae reared intensively in a controlled environment. Larvae of 4.53 mm initial length, 45 per dm(3) , were fed each day with live Artemia nauplii for 12, 18 or 24 h at 28degreesC. Final survival rates were very high in all treatment groups, ranging from 88.9 to 91.8%. Duration of daily feeding significantly affected growth and final condition, expressed by Fulton's coefficient (K) (P less than or equal to 0.05, Duncan's test). The fastest larval growth (17.6 mm total length, TL; 88.8 mg body weight, BW) and the best condition (K = 1.54) were recorded in the group fed 24 h each day. The second best results were attained with the larvae fed 18 h a day (16.5 mm TL, 67.9 mg BW, K = 1.40) whereas those fed 12 h daily grew the slowest (13.5 mm TL, 31.7 mg BW) and showed the worst condition (K = 1.19). Thus, to maximize growth and condition of tench larvae being reared at the optimal growth temperature, intensive 24 h feeding is necessary.