Consequences of Environmental Stressors on Hematological Parameters, Blood Glucose, Cortisol and Phagocytic Activity of Nile Tilapia Fish

Introduction: Under intensive fish culture of Tilapia, there appears to be susceptible various environmental stressors. Stress factors normally reduce growth and damage the biological system of the fish resulting in a great economic loss.

Aims: The study aimed at elucidating effects of lack of feedstuffs, overcrowding and protein deficiency on Tilapia physiology and production.

Study Design: Ninety Tilapia fish, half males and half females were randomly allocated into four treatments [control (C), protein deficiency (P), fasting (F) and overcrowding (O)].

Materials and Methods: Three aquaria were used for each treatment. Each aquarium has 6 fishes except in case of overcrowding each aquarium contained 12 fishes. Treatment lapsed for 30 days in C and P, 21 days for F and 14 days for O. Blood was collected for hematological traits and for biochemical attributes.

Results: There exists significant increase (p<0.05) in MCV values in fishes (males & females) exposed to deprivation of food. Moreover, males exhibited significant high MCV value when they were overcrowded. Mean values for MCV in males were 112.93, 123.45, 118.41 and 121.68 µm3 for C, F, P and O, respectively. Males didn’t express changes in MCH due to treatment. The values for MCH (pg) were; 35.15, 35.45, 34.15 and 35.74 pg for C, F, P and O, respectively. On the other hand, there exist significant (p<0.05) decreases in MCH values in overcrowded and protein deficiency-group. The respective MCH values in females were; 37, 35.05, 34.35 and 34.46 for C, F, P and O, respectively. Percentage of MCHC showed significant decreases (p<0.05) in treated males and females compared with control fish. Values of mean corpuscular hemoglobin concentration in males were 31.11, 28.92, 28.98 and 29.42 mg/dl for C, F, P and O, respectively. Similarly in females the respective values were; 30.99, 27.84, 28.16 and 29.21 mg/dl, respectively.

Conclusions: Adverse environmental stressors had negative impacts on different physiological parameters of Tilapia fish causing severe reduction in the productivity and consequent severe economic losses.