Napier grass (Pennisetum purpureum) and maize (Zea mays) bran were tested as low-cost inputs to earthem ponds and concrete tanks. In Experiment 1, fresh napier grass was given at 50kg dry matter (DM)ha-1 day- 1 alone and in combination with maize bran at 3% fish body weight day-1 and/or agricultural limestone (L) applied at 100 kg ha per 2 weeks. Treatments were applied over 181 days to a mixed-sex 1:1 polyculture of Tilapia rendalli and Oreochromis shiranus stocked at 2m-2 in 200 m2 ponds. In Experiment 2, fresh napier grass (NG) was given whole (WG), chopped (CG) or ground (GG) at 50 kg (DM) ha-1 day- 1 or in combination with maize bran (MB) at 3% fish body weightday- 1 for 108days to a mixed-sex polyculture of six T. rendalli and six Oreochromis karongae stocked at 2.4 m2 in 5 m3 tanks.
In Experiment 1, treatments which included a combination of napier grass and maize bran performed significantly better (P < 0.05) than did other treatments. Average extrapolated yield from NG + MB and NG-I-MB + L was 1729kgha-1 compared with 1255kgha-1 for other treatments. Average specific growth rates (SGR) for stocked T. rendalli and O. shiranus were 0.78% day-1 and 0.75%day-1, respectively, in NG + MB and NG + MB + L compared with
0.58% day 1 and 0.60% day " 1 in other treatments. Fry and fmgerlings contributed 47.7 ± 0.7% to the final catch weight of all treatments.
In Experiment 2, SGR values in CG + MB (1.46% day - 1 and 1.31% day - 1 for T. rendalli and O. karongae, respectively) were not significantly different from those for CG alone. CG treatment performed significantly better (P < 0.05) than other treatments. The addition of maize bran to CG