A Laboratory Bioassay of the Potential Effect of Rubber Extract (Hevea brasiliensis) on the Survival of Fingerlings of Oreochromis niloticus

Abstract

The potential effects of Hevea brasiliensis on the survival of fingerlings of Oreochromis niloticus were investigated in duplicate (A and B) using the water soluble fraction of the latex under laboratory conditions for 96 hours. The WSF of Hevea brasiliensis was tested against Oreochromis niloticus at 0, 8, 16, 24, 32 and 40mg/l in glass aquaria stocked with ten animals for 96 hours under observation for changes. Behavioural pattern exhibited by the fish include, loss of balance, restlessness, attempt at jumping out and hemorrhaged gills, respiratory difficulties and mortalities were observed in the WSF exposure groups, but not in the controls. LC₅₀ values were estimated at 28. 50 ± 0.2mg/l. There was significant difference in mortalities between the replicate group (p < 0.05), leading to conclusion that the organism in each batch responded differently to the toxic effect of WSF of Hevea brasiliensis latex.