Polyculture of Largemouth Bass (Micropterus salmoides) with Blue Tilapia (Oreochromis aureus): Using Tilapia Progeny as Forage

In this study, five, 0.04-ha ponds were stocked with advanced size largemouth bass fingerlings at densities of 124, 247, 494, 988, and 1136/ha. Tilapia brood fish were stocked at densities of 590/ha (male: female ratio was 1:3). Pond trials were conducted for a 6-month period, June to December 1985. Bass survival ranged from 40 to 89%. Bass stocked at densities 494/ha (low density) grew significantly larger than those at 988/ha (high density). Mean bass weights and percent weight gains at harvest in low versus high density ponds were 593 g and 3,318% and 120 g and 329%, respectively. High density bass ponds produced larger tilapia broodfish at harvest. The number of juvenile tilapia surviving in low density bass ponds was substantially greater (20,000 juveniles/ha) than in high density bass ponds (99 and 420 juveniles/ha). The higher survival of tilapia juveniles in low density bass ponds was the apparent cause of significantly higher turbidity (determined from secchi disc measurements) in these ponds. The results of this study suggest that forage/predator ratios, based on densities of female tilapia broodfish to bass, of 0.7 and 1.4 are suitable for controlling spawn and producing large tilapia or for producing large bass, respectively.