Fish farm technology 1. Brackishwater fish culture based on 'aquafeed'

A method has been evolved to enhance the production of natural feed in brackishwater fish farms by providing substrates for biogrowth ("aquafeed" production) which is a biomass complex consisting of sedentary and associated organisms of plant and animal species. The seasonal fluctuations of the aquafeed production over different substrates ranged as: 787-1830 g/coconut leaf (6 m super(2))/45 days, 16.0-072.9 g/glass panel (2 x 10 x 10 cm super(2))/30 days, 52-230 g/nylon mat (2 x 25 x 25 cm super(2))/30 days and 18.6-123.1 g/wooden block (6 x 10 x 10 cm super(2))/30 days. The average dry weight composition of the major components of aquafeed obtained in the present study was sand-silt-clay 40%, protein 22%, carbohydrate (water soluble) 1.8% and fat 3.35% (water content 85%). Mugil cephalus) of 1.85 cm reared in a 0.01 ha. pond and fed on aquafeed attained a size of 23 cm length and 146.73 g weight during one year. Survival rate was 54% at a density of 10000/ha. Salinity and temperature of the pond during the culture period ranged between 1.4 and 32.8 ppt and 28.1 and 36.5 degree C respectively.