Diagnosis of pathologies in chronic intoxication of Nile tilapia as a mechanism for optimizing aquaculture biotechnological process

Intensive technologies contribute to increased productivity in aquatic animal farming, but they also create a number of problems associated with increased stress on the fish body. This is due to the stress caused by specific aspects of the intensive approach. Nile tilapia (Oreochromis niloticus) is a widespread species that is well-suited for commercial cultivation due to its high growth rate, high market value, and significant resistance to biotic and abiotic stressors. While some studies have examined the effects of ammonium accumulation and heat stress on Nile tilapia productivity, the long-term impacts of these stressors on the immune system, particularly on the body of Nile tilapia, remain poorly understood. Ammonium chloride (NH4Cl) was used to simulate the effects of ammonium nitrogen on fish. The research was conducted on the experimental base of the small innovative enterprise OOO Eco-Tropic. The study revealed that ammonium nitrogen exposure leads to changes in liver function, affecting fish resistance indicators. In particular, typical hemorrhages were noted, which were morphologically combined with vascular congestion, degenerative changes in hepatocytes, necrotic degeneration and telangiectasia of the epithelium. In order to determine the degree of tissue damage, it is necessary to use additional quantitative methods in the future, such as biochemical analyses. Ammonium nitrogen intoxication resulted in a greater than four-fold increase in blood bilirubin levels. The revealed transformations can significantly impair liver function, thereby reducing the efficiency of commercial cultivation.