EVALUATION OF AMMONIA EFFECT ON BLOOD PARAMETERS, STRESS, AND GILL HISTOLOGY OF THE BANDED CICHILID (Heros severus)

Ahmad Termeh Yousefi¹, Hossein Khara^2*, Mohaddeseh Ahmadnezhad³
^1- Department of Fisheries, Science and Research of Guilan, Islamic Azad University, Rasht, Iran,
2- Department of Fisheries, Lahijan Branch, Islamic Azad University, Lahijan, Iran,
3- Iranian Fisheries Science Research Institute, Inland Water Aquaculture Research Center, Agricultural Research Education and Extension Organization (AREEO), Bandar Anzali, Iran

h.khara1974@yahoo.com

As a chemical stressor, increased ammonia concentration in water is a major problem in aquaculture which can cause non-specific physiological responses in the fish. If the appropriate concentration of ammonia is not taken is not account in aquaculture, it will be certainly followed by the production cuts. The present research aimed to determine changes in blood parameters and study the pathological effects of ammonia on gill tissue of the banded cichlid, Heros severus. For this purpose, 5 treatments of ammonia (0.1, 0.2, 0.4, 0.8, and 1.2 mg/l) with a control and three replicates were established. A total of 180 banded cichlid specimens were exposed to different concentrations of ammonia in 50-liter tanks for 12 hours. At the end of the trial, blood samples were taken from fish specimens for measurement of blood parameters and stress indices (glucose and cortisol). In addition, their gill tissues were sampled and studied. The results showed that white blood cells count reaches its peak in exposure to different levels of ammonia in Treatment 3 (P<0.05). The lowest red blood cells count was observed in Treatment 5 (P<0.05). Similar to red blood cells, hemoglobin and hematocrit showed a slight downward trend with the increase in ammonia concentration, which was not significantly different (P>0.05). Increased concentration of ammonia caused no significant difference between the five experimental treatments in MCV, MCH, and MCHC (P>0.05). Neutrophils and lymphocytes, like white blood cells, showed an upward trend at first and then started to reduce with increasing doses of ammonia (P<0.05). Monocytes and eosinophils also followed a variable and irregular trend, which was not significantly different (P>0.05). The results obtained from the measurement of stress indices indicated that cortisol increased in the first two treatments and then decreased in the next three treatments. In addition, glucose reached its minimum level in the first treatment and then showed a significant increase in other treatments (P<0.05). The results of histological studies revealed that tissue damages exacerbated with the increase in ammonia concentration from the control to Treatment 5, with the highest volume of damages in Treatment 5 (1.2 mg/l ammonia). The most common tissue damages observed in studied fish specimens included hypertrophy of lamella epithelial cells, adhesion of lamellae, lamella detachment and bulging, filament epithelium necrosis, severe necrosis in the lamella and filament epithelial, and necrosis and demolition of pillar cells. Finally, concentrations of ammonia tested on fish specimens in this study caused stress for the banded cichlid. Therefore, 0.1 mg/l dose of ammonia is recommended for the culture of the banded cichlid.

Keywords: Banded cichlid (Heros severus); Ammonia; Blood parameters; Stress; Gill histology