Diets of live zooplankton produce faster growing, more marketable Koi than either commercial diets or water enrichment, says a new study.
Scientists from the University of North Bengal undertook four 11-week growth trials during the winter, summer, monsoon and post-monsoon seasons in India to assess seasonal influence on growth and production of Koi fry.
Some fish were fed on live zooplankton, while others had either poultry manure or cow dung added to the water to trigger the growth of microbes: a control group was fed on a diet consisting of a commercial feed based on 32% crude protein.
Those fish fed on live zooplankton produced a significantly higher weight gain than all others, packing on more than twice as much weight as those fed commercial diets.
Zooplankton-raised fish also had much higher survival rates and produced more marketable fish - with lower levels of deformity - than those reared using other methods.
Fish fed on commercial diets had the highest level of deformity, suggesting that the diet used lacked key nutrients present in zooplankton.
For more information see the paper: Jha P, Barat S and K Sarkar (2006) - Comparative effect of live food and manured treatments on water quality and production of ornamental carp, Cyprinus carpio var. koi L., during winter, summer, monsoon and post-monsoon growout experiments in concrete tanks. Journal of Applied Ichthyology. doi:10.1111/ j.1439-0426.2006.00788.x