Readaptation of Silver Carp to Standard Conditions after Long-Term Toxic Ammonium Nitrogen Load over Some Generations

The readaptation of the crucian carp after some generations of successful adaptation in the reservoir contaminated by inorganic nitrogen compounds and its return to favorable environmental conditions was investigated. After the 3-month adaptation to standard conditions, all considered physiological parameters (organ indices and Fulton fatness) reached the control values. At the same time, biochemical parameters did not return to the initial physiological state. According to the hormones (cortisol, T3 and T4) and glucose content in blood plasma, it can be stated that the experimental specimens had the energy-saving metabolism. The experimental specimens developed somewhat other way of the excess ammonium nitrogen excretion from the organism. Thus, content of protein as the basis of ammonia transport, in the blood plasma was lower than in control. Over the readaptation period, the experimental specimens had the increased hemoglobin content in blood. Thus, within three months complete readaptation of carp did not take place, the biochemical state was the most revealing.