author(s)
Asim Ullah, Hameed Ur Rehman, Alam Zeb Khan, Ziafat Rehman, Saeed Ahmad, Mujaddad Ur Rehman, Asima Bakht, Zain Ul Abdin, Zona Amjad, Muhammad Fahim Qureshi, Javid Khan

abstract
Metals are of special concern because of their diversified effects and the range of concentrations that could cause toxic ill-effects to the fish. Generally, heavy metals exert their toxic effects in organisms by generating reactive oxygen species, causing oxidative stress. This paper emphasizes on the determination of 96-hr LC₅₀ value of Lead Nitrate for the fish, Oreochromis niloticus. The fish species were acclimatized in laboratory condition for 20 days. The stock solution of lead nitrate was prepared and fish were treated with different gradually increasing concentration of metals for 96 hours. The result showed that LC₅₀ of Lead Nitrate for the fish, Oreochromis niloticus 44 mg/l. the mortality of the fish is directly proportional to the concentration of the expose metals.