Growth performance of Oreochromis niloticus in combination with clariid catfishes in monoculture and polyculture

Abstract

The growth performance of Oreochromis niloticus in polyculture with clariid catfishes was studied. The experiment was designed as two (stocking ratio) by three (species combination) factorial in a completely randomised design. Monoculture of O. niloticus served as the control. Each treatment was replicated three times. The stocking ratios were 1:2, 2:1 clariid catfish to O. niloticus and the monoculture 0:1 .The 1:2 and 2:1 were the polyculture combinations of Heteroclarias + O. niloticus (HCON), Heterobranchus bidorsalis + O. niloticus (HBON), and Clarias gariepinus + O. niloticus (CLON), while the 0:1 was the monoculture of O. niloticus (ON) which served as control. Each tank was fertilized with poultry droppings and N.P.K. (15;15:15) fertilizers at the rates of 700kg/ha/week and 60kg/ha/week respectively. Fishes were fed supplementary diet containing 36% crude protein at 5% body weight daily. There was no significant difference (P>0.05) in the final weight gain of O. niloticus combined with the various clariid catfishes. There was a significant difference (P<0.05) between the polyculture and monoculture of O. niloticus with the polyculture being superior to monoculture in weight gain(ie 91.3, 75.3, and 11.8 for the 2:1, 1:2, and 0:1stocking ratios). The yield of O niloticus was significantly different (P<0.05) among the stocking ratios and species combinations. The O niloticus in 2:1 clariid catfish to O. niloticus gave a higher yield than the 1:2 and 0:1 stocking ratios (i.e. 526, 289 and 44433g/3m²/180days), 356 and 3740, 357, and 59g/3m²/180days for HCON, HBON CLON and ON only respectively. The average harvestable table size of over 150g (A_T value) was significantly higher for the 2:1, 1:2 and 0:1 stocking ratios (i.e. 83.86, 34.15 and 25, 87.57%) and 58.4, 56.29, 62.33 and 28% for HCON, HBON CLON ON only respectively. Unlike the 1:2 polyculture combinations, the 2:1 stocking ratio achieved partial recruitment control of O. niloticus. Water quality (temperature, dissolved oxygen, pH) were all within the acceptable limits for warm water fish. A preponderance of clariid catfishes to O. niloticus is recommended when higher A_T value of O. niloticus which translate to larger-sized tilapia is desired.

Keywords: growth, O .niloticus, clariid catfishes, monoculture, polyculture

Tropical Freshwater Biology Vol. 14 2005: 61-69