Changes in hydrochemical parameters of the aquatic environment and biochemical parameters of fish blood serum from the planting density in the ultrasound

In this work, 10 biochemical parameters of blood serum of rainbow trout grown in a system of closed-loop water supply installations (SLV) at various planting densities were studied: control (10.8 kg/m3), SLV No. 1 (14.4 kg/m3) and SLV No. 2 (18 kg/m3) in a chronic experiment lasting 60 days. It was revealed that with an increase in the planting density of fish to 18 kg/m3 over a period of 30 days, toxic nitrogen compounds in the form of nitrites accumulated in the cold-water system of the ultrasonic system, the concentration of which was 0.19 mg/l. Further, with the continuation of a long-term experiment, it was shown that on the 60th day in the water of UZV No. 1 and No. 2 outside the MPC there were indicators of nitrites and nitrates in concentrations of 0.1 and 0.16 mg/l, respectively, while not leading to a fatal outcome of the growing objects. It was shown that with an increase in the concentrations of nitrites and nitrates in the water in ultrasound No. 2, the biochemical parameters of fish blood exceeded the norm: the level of aspartate aminotransferase increased by 58%, creatinine – by 7.32%, alkaline phosphatase – by 64.1% and lactate dehydrogenase – by 37.8%, signaling a violation of the physiological status of the liver and kidneys. Based on the results of the work, it was determined that the study of 10 biochemical parameters of the blood of rainbow trout is an indicative system for determining the health status of fish during their cultivation under chronic stress due to increased planting density in the ultrasound.