Growth and gonadal maturation of Keeled mullet, Liza carinata, (Valenciennes, 1836) cultured at different salinities

The growth experiment was conducted in fish culture outdoor cement ponds (5X4X1.2) under controlled conditions and filled with water (20 m^3). The experiment was carried out through 210 days. Every day, about 15-20% of water content was replaced to maintain water quality. Fish in all ponds were fed about 5% of total fish weight on artificial diet contains 25% fish meal. Experimental salinities (5, 15, 25, and 40 ‰) in four ponds (triplicate design) were obtained by diluting sea water with dechlorinated tap water (by passing through active charcoal). Fish at salinities 5 ‰ and 40 ‰ exhibited greater growth in length (cm) 10.77±0.097, 11.39±0.088 and weight (gm) 12.3±0.319, 15.02±0.44, respectively (P 0.05). Fishes at salinities of 15 ‰ and 25 ‰ represented lower growth in length 9.15±0.23, 9.1±0.10 and weight 7.41±0.53, 7.83±0.29, respectively (P 0.05). It was found that salinity does not affect significantly the condition factor of the individuals. Condition factor was ranging from 0.93 to 1.03 and there were no significant differences (P 0.05) between fish that had been subjected to different salinity treatments. Gonad somatic index (GSI) was significantly influenced by salinity (P 0.05). The GSI for both males and females have nearly the same fluctuation trends which reached to the maximum level at salinity of 40 ‰ for both sexes; 8.9 for female and 2.1 for male. The highest coefficient b of length-weight relationship were 2.839, 2.847 for fishes at salinities 40 ‰ and 5 ‰, respectively they closed to 3 it is indicated that isometric growth. The gonad maturation of salinity 5‰ reached to ripe stage for male and yolk vesicle stage for female but it reached to ripe stage at salinity 40‰ for both sex. These results suggest that Liza carinata is a suitable candidate for low salinity brackish water aquaculture. This could lead to significant cost savings when rearing fish inland.