Effect of water exchange on water quality and the production of ornamental carp (Cyprinus carpio var. koi L.) cultured in concrete tanks manured with poultry excreta
Abstract
The effect of water exchange on water quality, plankton abundance, and the production of koi carp, Cyprinus carpio var. koi L., cultured in outdoor concrete tanks manured with poultry excreta was determined. Individual weight gain and survival rates of fish (initial weight 0.09 ± 0.02 g) were compared among five culture regimes, where a volume of 100 dm3 water was exchanged: (1) every day (WE1); (2) every alternate day (WE2); (3) two times a week (WE3); (4) once a week (WE4); and (5) a control treatment with no water exchange (NE). Significantly higher concentrations (P < 0.05) of conductivity, NH4-N, NO2-N, NO3-N, PO4-P and bicarbonate alkalinity were recorded in the NE treatment. Plankton volume was highest in WE1 (P < 0.05). The weight gain and number of koi carp of marketable size were significantly higher (P < 0.05) in WE1. There was a significant difference in the survival of koi carp among the treatments ranging from 60.43% (NE) to 95.21% (WE1). The results suggest a water exchange of 100 dm3 daily (WE1) was the most effective for koi carp tanks manured with poultry excreta as better water quality and greater plankton abundance were both maintained in the system.
CORRESPONDING AUTOR: Dr. Sudip Barat, Aquaculture and Limnology Laboratory, Department of Zoology, University of North Bengal, Siliguri 734 430, West Bengal, India, Tel : +91-0353-2582124, Fax : +91-0353-2581546;E-mail: sudipbarat@rediffmail.com
