EFFECTS OF STOCKING DENSITY OF GRAY MULLET (Mugil cephalus Linnaeus, 1758) ON PRODUCTION AND NUTRIENT RECOVERY IN AN INTEGRATED FARMING OF WHITE SHRIMP (Litopenaeus vannamei Boone, 1931)
Shrimp farming has been facing a lot of problems consisting of environmental pollution, shrimp diseases outbreak, and overuse of chemical during operated culture activities. Polyculture is considered as an important alternative to utilize the uneaten feed and decrease organic pollution and prevent shrimp disease in shrimp farming. In Vietnam, Gray mullet (Mugil cephalus Linnaeus 1758) is being considered as a novel candidate for polyculture, especially with white shrimp because of its rapid growth rate, eating habit, and availability fingerling. The aim of this study was to assess the effects of different densities of gray mullet on production and nutrient recovery in the white shrimp integrated culture system.
An experiment (75 days) was conducted in twelve composite tanks (5 m3), with triplicates per each treatment (Table 1) and three tanks were stocked only white shrimp as control treatment. Shrimp (body weight of 0.50 g) were acclimated to laboratory conditions for 2 weeks prior to the experimentation. Gray mullet (Mugil cephalus) fingerling were reared in laboratory condition until they reached experimental size of 1.50 g by commercial diet (Growbest Co. Ltd. Vietnam). Water from the sea was filtered through a sand filter and pumped into a container tank (50 m3) where seawater was diluted with groundwater to produce experimental seawater which salinity of 15‰. Aeration was supplied in cultured tanks by air stones throughout the experimental period. Shrimp were fed four times a day using 35% protein commercial pellet (Growbest Co. Ltd. Vietnam) with feeding rate was 3 to 10% of biomass. No external feed was given to the fish during the experiment.
After 75 days, treatment II (10% gray mullet) shrimp and fish had significantly (p < 0.05) higher in the biomass, the weight gain, and the Nitrogen recovery compared to all other treatments (Table 2). These results showed that white shrimp can be cultured with gray mullet at the stocking density of 10% biomass of shrimp to improve overall productivity and nutrient utilization efficiency.