Subacute intoxication of a deltamethrin-based preparation (Butox) 5% EC) in monosex Nile tilapia, Oreochromis niloticus L.

The monosex Nile tilapia, Oreochromis niloticus L., was exposed to subacute concentration (1.46 microg/l) of a pyrethroid insecticide, deltamethrin for 28 consecutive days. Behavioural, clinical, haematological, serum biochemical and histopathological consequences were assayed at a regular interval of 7 days. The abnormal behavioural responses and toxic symptoms were described. Exposure to deltamethrin not only significantly decreased lymphocyte and basophile percentages, total leucocytic and total erythrocytic counts, haemoglobin percentage and packed cell volume value, but also caused serious effects in the form of hypoproteinaemia, hypoalbuminaemia, hypercholesterolaemia, hyperglycaemia and significantly increased serum aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase activities. Moreover, the histopathological results indicated that the haemobiotic organs were affected by deltamethrin, primarily liver and gills. Our data suggest that subacute exposure to deltamethrin exerts a serious metabolic distress on the fish corresponding to the exposure period. In addition, the assayed parameters and histopathological findings can be as good biomarkers of pyrethroid ecosystem pollution.