Effect of Replacing Fishmeal with Spirulina on Growth, Carcass Composition and Pigment of the Mekong Giant Catfish

Spirulina has been commercially cultivated because of its high nutritional content. It can be considered a nutritional supplement for humans with various health benefits, and a feed supplement for animals having economic benefits. In aquaculture, Spirulina has been used to improve the immune system and increase the survival rate in juvenile commercial fish, as well as to increase their flesh pigment. From these applications, Spirulina could be used to replace high protein feed ingredient such as fishmeal and soybean meal to save the costs of feed. The Mekong Giant Catfish (Pla Buk), Pangasianodon gigas Chevey, is one of the largest species of freshwater catfish in the world. This fish is an endemic species in the Mekong River and its branches. At present, Thailand could culture this fish on a commercial scale. This study was conducted to investigate replacing fishmeal with Spirulina, at 0, 15, 30 and 100%, and to evaluate growth, feed utilization and pigment in flesh of fish. The results showed that the proximate composition of the various feeds (4 formulas) had similar nutritional value. Average daily gain, specific growth rate and feed conversion rate were not significantly different. However total biomass increase of fish fed with Spirulina 0% was significantly lower than fish fed with Spirulina 15, 30 and 100% (p<0.05). The standard length of the fish and weight in terms of flesh, gut and stomach were not significantly different. As well, flesh pigment and carotenoids were not significantly different.