Chlorella vulgaris as Protein Source in the Diets of African Catfish Clarias gariepinus

Plant proteins substitutes of fishmeal in aquafeed are usually lacking in some essential amino acids and fatty acids. The microalgae Chlorella vulgaris has good-quality protein with amino acids rich in methionine, lysine and alanine. Four novel diets having C. vulgaris as the main source of protein were produced for African catfish Clarias gariepinus with an initial average weight of 1.09 +/- 0.05 g. The diets were labeled Feed 1 (F1) to feed 4 (F4). The treatment diets were included 25% (F1), 15% (F2), 5% (F3) and 0% (F4) green algae meal. The basal ingredients of the feed were corn (maize) included as F1, 40%, F2, 43%, F3, 53% and F4, 43%; and millet meal, which varied in F1 as 23%, F2, 30%, F3, 30% and F4, 30%. The ingredients were preconditioned at 110 degrees C and pelleted. Post-fingerling African catfish were stocked at 10 fish per aquarium. There were three replicate aquariums for each feed type and the fish were fed for 60 d. The specific growth rate was best for the catfish fed with 25% C. vulgaris diet 7.86 +/- 0% day(-1), and worst at 6.77 +/- 0.07% day(-1) for the control group F4, 0% algal meal. The food conversion ratio (FCR) was lowest (1.88 +/- 0.02) for 25% algal meal diet (F1) and highest (2.98 +/- 0.01) for the 0% algal meal diet F4. Similarly, catfish had average weight gain of 121.02 +/- 0.04 g for those fed with F1 compared to 62.50 +/- 0.0 g for those fed with 0% algae F4. Protein efficiency ratio was highest for the F1-fed fish (2.46 +/- 0.22) and lowest for those fed with F4 (2.02 +/- 0.09). The hepatosomatic index was lowest for F1-fed fish (1.48 +/- 0.01) and highest for catfish fed with F4 (2.50 +/- 0.59). Based on the results, C. vulgaris is a good protein source for African catfish and can also substitute fishmeal in the catfish diets.