Piscicidal Effects of Lepidagathis alopecuroides on Mudskipper, Periophthalmus papillio from the Niger Delta

The piscicidal effects of dried leaves of Lepidagathis alopecuroides (1.0, 2.0, 4.0 and 6.0 g L 1) on mudskipper, Periophthalmus papillio (mean total weight, 17.29 5.69 g, SD) were assessed in a non-renewable bioassay after 12 h exposure. Exposed fish showed dose-dependent hyperactivity with increased opercular and tail beat frequency with copious accumulation of mucus on the gills and skin. Time to death ranged from 18-37 min and the cidal action of the plant were influenced by the exposure concentration (p< 0.001) and weight of the fish (p< 0.01). Pathological changes were recorded only in the gill, stomach and brain of exposed fish and appeared to be dose-dependent. There was necrosis of epithelial cells of the mucosa lining, extensive loss of mucosa glands, oedema of submucosa and loss of fatty tissues in the intestine. The gill lamellae were clubbed and atrophied with extensive necrosis, hyperaemia and hyperplasia of mucus cells. The oedematous distensions in the lamellae were infiltrated by mono- and polymorpholonuclear leucocytes. Mild to severe oedamatous distensions were observed in the brain of exposed fish. However, the gill appeared to be the main site of action of the plant material. The high toxicity of the plant material to mudskipper seems to suggest that non-target species may not be spared during application in the environment.