Carbon, nitrogen and phosphorus budgets of silver carp Hypophthalmichthys molitrix with the co-culture of grass carp Ctenopharyngodon idella

Abstract

Fish farming activities have resulted in increasing nutrient pollution and subsequent deterioration of water quality in aquatic environments worldwide. Silver carp Hypophthalm ichthys molitrix can efficiently remove excessive nutrient pollution by filtering the suspended particulate organic matter. To evaluate the feasibility and capacity of using silver carp as biofilters to remove the wastes released from the farming of grass carp Ctenopharyngodon idella, 3 mesocosms comprising grass carp and silver carp were developed. Carbon (C), nitrogen (N) and phosphorus (P) budgets of silver carp were measured every month from May to October in 2011. Owing to the changes in exogenous environmental conditions and autogenous physiological status such as water temperature, dissolved oxygen level and feeding behavior, the metabolic acquisition and expenditure of silver carp exhibited obvious temporal fluctuation. For a standardized silver carp with 30 cm body length, the average scope for growth of C, N and P were 54.83, 8.73 and 0.85 mg h-1, respectively. Total nutrient assimilation capacities throughout the experimental period for C, N and P were 236.86, 37.70 and 3.67 g, respectively. Our findings show that silver carp with the coculture of grass carp provides an eco nomic and environmental win-win resolution to enhance aquaculture production and reduce organic pollution in water.