Abstract
Environmental contaminants, such as heavy metals and pesticides, are the most important toxic compounds of aquatic habitats. Heavy metals enter the aquatic environments via natural and anthropogenic pathways while the only source of pesticides is the anthropogenic usage of different types of pesticides including fungicide, insecticide and herbicide. Fish larvae and fingerlings are the most vulnerable life stages of fish which could be severely affected by pesticides as non-target organisms as well as by heavy metal pollution. The most important tissues affected by these pollutants are the gill, kidney and liver. Histopathological alterations of these vital organs could affect the survival rate, biological activities, osmoregulation, reproduction, buoyancy, etc., which finally could lead to failures in stock recruitment and population changes.