Growth Performance of the Mangrove Red Snapper (Lutjanus argentimaculatus) in Freshwater Pond Comparing Two Stocking Densities and Three Feed Types

Abstract

The mangrove red snapper Lutjanus argentimaculatus (Forsskål 1775) is a high value, euryhaline marine fish with potential as a species for freshwater aquaculture. This study evaluated the growth and cost efficiency of the species in a freshwater pond in two experiments with three replications: (a) comparing stocking densities: (1) 0.5; (2) 1; and (3) 3 fish fish•m-2 reared for six months fed three times a day with trash fish to apparent satiation; and (b) comparing feed types: (1) trash fish; (2) moist diet; and (3) formulated dry pellet at a stocking density of 1 fish•m-2 fed to apparent satiation three times a day for seven months. The stocking density (SD) experiment showed significantly higher weight gain, absolute growth and specific growth rate (P<0.05) in 0.5 fish•m-2 SD (184.9 g; 1.04 g•day-1; 2.50%/day) than 3 fish•m-2 SD (172.7 g; 0.96 g•day-1; 2.38 %•day-1). No significant difference was detected between 0.5 fish•m-2 SD and 1 fish•m-2 nor between 1 fish•m-2 and 3 fish•m-2 (P>0.05). Survival rate (SR) and feed conversion ratio (FCR) were not statistically different between treatments (P>0.05), which ranged from 78% to 92% and 5.0 to 5.9, respectively. Cost analysis showed high net returns for 1 and 3 fish•m-2 SD but low in 0.5 fish•m-2 SD. The feeding experiment study showed that feed types significantly affected weight gain, SGR, and SR (P<0.05). Snappers fed with trash fish attained significantly higher mean absolute growth (298.2 g) and SGR (1.81%/day) than those fed moist feeds (232.8 g and 1.61%/day, respectively) and formulated feeds (236.1 g and 1.51%/day, respectively). The survival rate was significantly higher in snappers fed trash fish (93.33%) and dry pellets (94.00%) than fed moist feeds (81.34%). FCR in trash fish, moist and dry pellet treatment was 6.4, 6.3, and 2.7, respectively. Cost analysis showed high net returns for trash fish and formulated pellet fed snappers but low in moist diet feed treatment. Cost-benefit analysis showed the feasibility of mangrove red snapper for freshwater aquaculture at a recommended stocking density of 1 to 3 fish•m-2 using trash fish, moist diet, or formulated dry pellet.