Some adaptive reactions of the prussian carp Carassius auratus gibelio (Bloch) based on the excessive load of ammonium nitrogen

Purpose. The aim of the study was to find a difference in morphophysiological parameters and in the accumulation of energy-intensive substances in Prussian carp (Carassius gibelio Bloch, 1782), which existed at different times and at different concentrations ofallochthonous nitrogen in water. Methodology. In the course of the work, following morphological, physiological and biochemical parameters of the Prussian carp were determined: condition factors, hepatic and splenic indices, protein, lipid and glycogen content in fish organs and tissues, and glucose content in blood plasma. Collection and processing of ichthyological materials were carried out in accordance with generally accepted methods. Findings. The conducted studies showed that at a significant concentration of ammonium nitrogen up to 24.3 mg N/dm3 and with an increase in the adaptation time (from 3 months to several generations), the even-aged groups of fish had a difference in body length and weight that was confirmed by Fulton’s and Clark’. In the Prussian carp with the smallest and greatest adaptation time (3 months at a concentration of 24 N/dm3 and in several generations) to the ammonium nitrogen concentration of 48 mg N/dm3, the hepatic index was reduced (by 8 and 22.7%) compared to control, while the hepatic index, by contrast, increased compared to control to a concentration of 24.3 mg N/dm3 in fish adapted for 3 years. In all experimental groups of the Prussian carp, stable protein content in muscles was noted. After adaptation of fish during 3 months, lipid content in the liver was slightly higher than reference values, however, after adaptation during 3 years, lipid accumulation was significantly lower than control (by 35%), and in fish with long-term adaptation, lipid content in the liver approached reference values. Glycogen content in the liver of the experimental fish gradually increased with the duration of adaptation, however, with long-term adaptation to ammonium nitrogen concentration of 48 mg N/dm3, glycogen accumulation also approached the control. Originality. For the first time, the adaptive features of the Prussian carp in terms of morphophysiological indices have been studied under a prolonged exposure to high concentrations of ammonium nitrogen. Practical value. The obtained data can be used to understand the peculiarities of adaptation of cyprinids (for example, Prussian carp), to their existence in reservoirs affected by excessive action of nitrogen compounds. This will allow us to evaluate the conditions, under which new resistant fish populations are formed.