If you decide to clean the caught fish, but were surprised to find that there are worms inside it, then the fish was sick with ligulosis. Fish ligulosis is caused by tapeworms and is a dangerous disease that can endanger the existence of fish in freshwater bodies.
If belt worms live in the abdominal cavity of the fish (belt-like helminths, plerocercoids), then the fish is sick with ligulosis. The life cycle of worms includes the change of several hosts. Piscivorous birds become the final hosts, and fish play only the role of an intermediate host. As a rule, tapeworms live in the digestive tract of freshwater fish: bream, rudd, roach, crucian carp and other cyprinids.
What does an infected fish look like?
Fish infected with tapeworms quickly weakens, it has a violation of the basic physiological functions of the body, up to complete atrophy of vital organs. Usually, fish with ligulosis swim upside down or on their side near the shore or in shallow water - it is easier for them to get food there. Outwardly, the fish does not look the best. Its abdomen is swollen, hard enough to the touch. At the same time, the fish itself, in comparison with its other counterparts, has a much lower body weight. She is emaciated and underdeveloped. When a strong excitement begins on the water, the weakened fish cannot go to the depth and remains swimming on the surface, where it is nailed to thickets of reeds, snags, etc. It happens that from the abundance of worms, the stomach wall of the infected fish breaks and the parasites go into the water. The final conclusion about ligulosis can be made only after opening the fish and detecting helminths in its digestive tract.
Most often, mass infection of fish with tapeworms occurs in low-flow reservoirs - ponds, lakes, estuaries, etc. Since fish sick with ligulosis move sluggishly and swim on the surface, they often become prey for fish-eating birds. In the body of birds, worms find their last resting place, where they end the cycle of their life development.
The life cycle of helminths
Externally, belt-like worms look like yellowish or white worms about an inch thick and 5 to 8 centimeters long. At the front end of the worm there are special organs with which it is attached to the organs of its host. The life cycle of plerocercoids begins with the fact that sexually mature worms lay eggs in the intestines of fish-eating birds (pelicans, gulls, cormorants, etc.). From there, the eggs of parasitic worms enter the reservoirs, where the larvae emerge from them. The larvae of helminths are swallowed by the first intermediate hosts - microscopic crustaceans. Fish eat crustaceans and become infected with ligulosis themselves. In the body of fish, worms grow to significant sizes and at the end of their life cycle enter the intestines of birds.
