Water hyacinth ( Eichhornia crassipes) leaves as an alternative protein source for feeding early phase of Tilapia ( Oreochromis niloticus)

Abstract

Water hyacinth (Eichhornia crassipes) is a fast growing invasive aquatic plant often covers water bodies. It has been a problem worldwide. Fast-growing and rapidly expanding omnivorous tilapia is likely the suitable species for aquaculture. Since the fish farmers are adversely affected by high cost feed, the use of water hyacinth as a protein source in fish feed could offer solutions to both the problems. The present study therefore was carried out to perceive the use of water hyacinth as a cheap protein source in the diet of tilapia (Oreochromis niloticus). Four types of fish feeds were formulated replacing the fish meal and soybean meal by water hyacinth at 0% (control, feed 1), 5% (feed 2), 15% (feed 3) and 20% (feed 4). Two weeks old tilapia fry of 0.8 g±0.3 g mean body weight were stocked in 12 tanks in four treatments, each with three replicates and fed with respective feed at the rate of 4% of body weight for 63 days (Each tank was stocked with fifteen tilapia fries). Body weight and body length of each fish were measured every fortnight while the initial measurement was taken after one week of acclimatization period. Feed cost for one kg of each feed samples was also calculated. The results revealed that the feed conversion ratio (1.54±0.18, 1.46±0.25, 1.45±0.16 and 1.46±0.42) and growth rates (0.11, 0.106, 0.106 and 0.124 g/day) among fish groups fed with feed 1, 2, 3 and 4 respectively were not significantly different (P>0.05). Costs per kg of feed decreased with the increasing of replacement of fish meal by water hyacinth i.e. Rs. 120, 110, 93, and 84 respectively. There were no significant differences in feed utilization among four types of feed by the replacement of protein source with water hyacinth. Thus, water hyacinth leaves could be used to replace 20% of the high cost protein source in the diet of tilapia.