Hormonal and haematological responses of <i>Clarias gariepinus</i> (Burchell 1822) to ammonia toxicity

Abstract

This study assessed hormonal and haematological responses of Clarias gariepinus to ammonia toxicity. Laboratory study of haematological responses of adult C. gariepinus to sub-lethal level of ammonia (2.2 g/l) at different exposure hours (0, 6, 24, 48, 72, 96 h) were carried out. Blood samples of C. gariepinus were collected at each exposure hour and evaluated for primary and secondary stress indicators. Data obtained were subjected to simple descriptive analysis and analysis of variance. Plasma cortisol level of C. gariepinus increased significantly (P < 0.05) from 0 h (01.0 ± 0.1 ng/dl) to 48 h (154.0 ± 1.0 ng/dl) after which it decreased and stabilized at 72 h (106.0 ± 1.1 ng/dl). Packed cell volume (PCV) and Red blood cell (RBC) were elevated after 6 h of exposure and decreased significantly (P <0.05) at 48, 72 and 96 h of exposure in fish exposed to sub-lethal level of ammonia. The mean plasma glucose level recorded at 0 h (95.00 ± 1.00 mM) decreased significantly (P < 0.05) with the lowest mean value of 37.00 ± 1.05 mM obtained at 96 h of exposure. Haematological and hormonal balances of adult C. gariepinus were affected under short-term exposure to ammonia toxicity.