Acute toxicity, behavioral changes, and histopathological effects of deltamethrin on tissues (gills, liver, brain, spleen, kidney, muscle, skin) of Nile tilapia ( Oreochromis niloticus L.) fingerlings

Deltamethrin, a synthetic pyrethroid contaminating aquatic ecosystems as a potential toxic pollutant, was investigated in the present study for acute toxicity. The purpose of this study was to evaluate LC 50 values of deltamethrin on Nile tilapia ( Oreochromis niloticus L.) fingerlings and investigate histopathological responses of fish exposed to deltamethrin. The 48 h LC 50 value for Nile tilapia fingerlings was estimated as 4.85 μg/L using static test system. In addition, behavioral changes at each deltamethrin concentration were observed closely. All fish, exposed to 5 μg/L deltamethrin revealed severe morphological alterations in the gills and liver. In the gills hyperemia, fusion of secondary lamellae and telangiectasis were observed; whereas hydropic degenerations in liver were observed in all examined fish. The results are significant for reporting acute deltamethrin toxicity in terms of behavioral and histopathological changes: Deltamethrin is highly toxic to fingerlings. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 614–620, 2006.