Abstract :
Blue tilapia, Oreochromis aureus were experimentally co-cultured with channel catfish, Ictalurus punctatus in floating cages, without supplemental feeding. Tilapia were stocked on April 20, 1995 at the equivalent of 5000 ha^-1 and channel catfish fingerlings were stocked on Mar. 20, 1995 at 27500 ha^-1. After harvest on Oct. 23, 1995 (185 d), tilapia averaged 437.7+ 4.26 g each. From a stocking size of 24.9 + 5.16 g, the daily growth was 2.2 + 0.23 g.d^-1. Improvements in water quality in co-culture were reduced levels of pH, TAN (total ammonia-nitrogen) and UIA (un-ionized ammonia). Aeration in co-culture ponds was significantly higher in August. Chlorophyll a was not significantly different. Mean net combined yield in co-culture ponds, with the addition of 2118.55 + 367.15 kg.ha^-1 tilapia, was significantly higher, 12001.64 + 767.43 vs. 10,055.74 + 734.70 kg.ha^-1, than in monoculture. FCR (food conversion ratios) for catfish were not significantly different; however, with tilapia included they were significantly lower, 1.58 + 0.11 vs. 1.85 + 0.85. Blue tilapia were beneficial to production and outperformed Nile tilapia in a similar system by reaching marketable size (0.4 kg) with no additional feed.
