Activity of energy and carbohydrate metabolism enzymes in Rainbow Trout fingerlings (<i>Oncorhynchus mykiss</i> Walb.) when feeding two types of commercial feed

We studied the activity of energy and carbohydrate metabolism enzymes (cytochrome c oxidase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, 1-glycerophosphate dehydrogenase, pyruvate kinase, aldolase) in the muscles and liver of rainbow trout of three size groups aged 5, 10 and 12 months under the influence of two types of commercial feeds with different composition. The levels of activity of the enzymes G6PDH, 1-GPDH and aldolase in the liver were significantly higher in fish from the “Feed №2” group. The identified differences in the activity of enzymes in the liver of fish suggest that feed №2 to a greater extent (compared to feed №1) promotes the use of carbohydrates in lipid biosynthesis. Differences in the activity of the enzymes COX, LDH, aldolase, G6PDH and 1-GPDH in the liver and muscles of fish depending on the month of sampling and belonging to the size group are most likely associated with changes in the metabolism of fish as their weight increases towards generative metabolism.