A comparison of the yield and yield economics of three types of semi-intensive grow out systems, in the production of Heterobranchus longifilis (Teleostei: Clariidae) (Val. 1840), in Southeast Nigeria

The yield and yield economics of three types of semi-intensive catfish grow out systems in southeast Nigeria were compared. These were: an integrated aquaculture-agriculture system, a commercial feed based system using locally produced pellets, and traditional grow out techniques. They were designated treatments 1, 2, and 3 respectively. Replicate new ponds were stocked with 160 Heterobranchus longifilis fingerlings and 10 adult Oreochromis niloticus (5 male and 5 female), per treatment. Soybeans were planted at the beginning of grow out to produce grains used as feed supplement in treatment 1. This was done in two consecutive 1-year grow out periods. The feed was prepared by partially substituting the feed ingredients used in treatment 3 with the soy grains. The soy plant matter was used as additional fertilizer. Pond age significantly influenced soy grain and plant matter yield, soy proportion of feed, and its soy-derived protein content (p<0.01). H. longifilis yield was significantly affected by treatment (p<0.001). In treatment 1, first year cost:benefit was 1:0.48 over variable cost and 1:0.41 over total cost. Second year values were 1:1.39 and 1:1.18 respectively. Cost:benefit in treatment 2 was 1:1.11 over variable cost in both years. Over total cost it was 1: 1.03 and 1: 1.05 in the first and second years respectively. In treatment 3 first year cost:benefit was 1:0.45 and 1:0.17 over variable and total costs respectively. Second year values were respectively 1:0.92 and 1:0.68, with pelleted feed accounting for 66% and 62% of variable and total costs respectively. Treatment I is recommended for adoption as an intermediate step in H. longifilis grow out in southeast Nigeria, until the pelleted feed-driven system becomes profitable. (C) 2007 Elsevier B.V. All rights reserved.