Experimental verification of the effect of physical condition of Gobio gobio (L.) on the growth rate of micropopulations of Gyrodactylus gobiensis Gläser, 1974 (Monogenea).

It has been verified experimentally that the growth rate of G. gobiensis micropopulations is markedly affected by the physical condition of the host (Gobio gobio). If the fish were weakened by 50% oxygen deficiency and lack of food, the number of parasites increased much more rapidly than on the fish also unfed but kept in water with 100% oxygen content. If the fish weakened by oxygen deficiency were intensively fed, the growth of the parasite micropopulations started to slow down after 4-5 days. When the feeding was stopped, the number of parasites increased again after 10-11 days. These time shifts seem to be associated with the physical condition of the host improved by feeding or worsened by starvation.