The effect of zeolite (Clinoptilolite) in removing ammonia lethal concentration in Rainbow Trout (Oncorhynchus mykiss)

Clinoptilolite efficiency on absorption of ammonia in rainbow trout was studied. The fish specimens weighted 9.5-21g and were exposed to four different concentrations of total ammonia as N-NH4 including: 10, 15, 20, and .25mg/l. A group of 13 fish was considered as control. Lethal concentration was determined after 24 hours. Under stable temperature and pH conditions (T= 16±1 C, pH= 7.7±1), the lethal concentration of total N-NH4 was 25mg/l (as ionized N-NH3=0.44mg/l based on temperature and pH). In lethal concentrations of ammonia, different amounts of zeolite (2, 5, 10, 13 and 15g/l) were used. Application of 15g/l of the zeolite prevented mortalities in the fish. A significant difference was found in reduction of total ammonia and total hardness through application of zeolite after 24 hours (P<0.01). The maximum mortalities occurred in early time of experiment. The histopathological lesions of gill, kidney and liver were studied.