This experiment determined the toxicity and behavioural changes of glyphosate aquatic herbicide (Force up) on African catfish Clarias gariepinus sub adult. A total of 120 live and apparently healthy Clarias gariepinus sub adult measuring 18.3-30cm standard length and average weight of 123g was randomly distributed into twelve (53.5cm X 33cm X 34cm) glass tanks of 60litres capacity each were filled with 20litres aerated bore-holes water, Six treatment in duplicate was set up for the experiment. Ten (10) Clarias gariepinus sub adult was distributed randomly in triplicate per treatment for experiment involving the sub adult Clarias gariepinus. The toxicant was introduced at different concentrations (0mg/l, 40mg/l, 70mg/l, 100mg/l, 130mg/l, 160mg/l) in triplicate per treatment. Fish mortality and behavioral changes was monitored and recorded for the first 24hours, 48 hours, 72 hours and for the 96hours. The inability of the fish to respond to external stimuli was used as an index of death. Dead fish were removed immediately with a scoop net to avoid contamination due to rotting. Behavioral changes exhibited by the fish include erratic swimming, air gulping, loss of reflex, molting, discoloration, barbel deformation and excessive mucus secretion in fish exposed to higher concentration of glyphosate aquatic herbicides. Histopathology of the organs after 96 hours; In the liver, there was nuclear vacuolization (NV) with irregular shaped nuclei, moderately damaged tissue and hepatocyte (H) regeneration which indicates that recuperation is still possible while in the skin; there was cellular abnormalities, shrinkages, hypertrophy of tissue, absence of dermal layer and necrosis. The 96h LC50 of glyphosate aquatic herbicide (Force up) to Sub Adult African Catfish Clarias gariepinus is 123.784mg/l with the maximum safe concentration ranged between 1.24mg/l to 12.38mg/l, the safe level of a compound is derived by multiplying the 96h LC50 with an application factor of 0.01-0.1. Such application factor are applied to acute toxicity test data to estimate the concentration that is safe for chronic exposure. The results of the study revealed that Glyphosate aquatic herbicide (Force up) is toxic to fish organs and causes histopathological changes in different organs such as skin and liver; therefore, indiscriminate use by farmers should be discouraged particularly in aquatic bodies.
Keywords: Hypertrophy, Glyphosate, Histopathological, Hepatocyte, necrosis