Successful gonadal development and maturation of tench (Tinca tinca L.) in small concrete ponds

Abstract

Summary The experiments were performed in a tench farm from autumn until the spawning season (June–July). Tench broodstocks from natural habitats were maintained in 25 × 6 × 1 m concrete ponds and fed on commercial trout pellets. Females and males were separated and maintained under natural photoperiod and temperature conditions at densities around 2 kg m−2. Water flow throughout was supplied at the rate of 15 L s−1. When females showed external signs of advanced gonadal development, induction of spawning was made by luteinizing hormone releasing factor (LH-RH) synthetic analogue administration at three different periods of the reproductive season (June–July). A single intramuscular injection (20 μg kg−1 body weight) was administered to 110 mature females selected from a total of 150. The females were stripped 42 h (22°C) after hormone administration. The mean rate of stripped females to the number injected was 77%. Mean relative egg weight in relation to the weight of the stripped females was 5.61%. More than 90% of the males provided semen without hormonal induction. Differences in egg production and external egg quality were observed at different times of the spawning period. It was proven that tench maintained in small concrete tanks and fed on artificial diets were able to reach gonadal maturation.