Toxic effects of chlorpyrifos on the growth, hematology, and different organs histopathology of Nile tilapia, Oreochromis niloticus.

Chlorpyrifos is a widely applied insecticide that permeates on most waterways and affects aquatic organisms. The growth performances, hematological and histological impacts on Nile tilapia, Oreochromis niloticus following a 60 day of exposure to varying concentrations of chlorpyrifos 20 EC (T 1 08 µgL⁻¹, T 2 16 µgL⁻¹, and T 3 32 µgL⁻¹) were compared to a control T c 0 µgL⁻¹. The 96-hour LC50 of chlorpyrifos 20 EC was calculated as 46.80 μgL⁻¹. The water quality parameters were recorded regularly. The value of dissolved O 2 and NH 3 stayed rather steady, although temperature varied considerably. It was revealed that as chlorpyrifos levels go up, the percentage of weight gain (WG %), specific growth rates (SGR), and survival rate decreases. The control group T c had the highest percentages of SGR weight (1.16 ± 0.58) and the T 3 group had the lowest percentages of SGR weight (0.25 ± 0.77). The hematological assessment showed significant differences of hemoglobin concentration, white blood cell counts and red blood cell numbers between chlorpyrifos treatment and control group (P < 0.05). Histological alterations in the liver, gills, and muscle tissues reported to be worse for T 3 as compared to others. There were no statistical differences in GSI, HSI values between control and treatment groups. The chlorpyrifos 20 EC was shown to be highly toxic to O. niloticus at sub-lethal dosages. [ABSTRACT FROM AUTHOR]