Lerneosis is a parasitic disease that is provoked by copepods. On aquarium fish, two species of crustaceans most often parasitize: esocina and cyprinacea.
The second species is considered to be a specific disease for goldfish, safe for other fish, but in the aquariums of these parasites they were found in tsilaz and goldfish. Crusta esocina is not very selective.
To kill a small fish is enough one or two parasites, an adult – up to 4 pieces.
The parasite develops without an intermediate host. A fertilized female parasite releases eggs into the water, out of which extremely mobile nauplii emerge.
For 5 days the nauplii of the lerinea swim freely in the aquarium and live off yolk stocks. At this time, many changes occur in their body, during which the parasite is actively developing.
It is during the stage of active development that the parasite larvae must necessarily attach themselves to the gill covers or the skin, because no further metamorphosis will occur.
Feeding on the fish’s tissues, the parasite grows and changes, turning into a cyclops and reach sexual maturity. After fertilization of the female, the male dies.
Through the skin of the victim, the female penetrates the carriers. This leads to the beginning of active changes in the structure of the parasite’s body.
The weakly visible head part will be separated from the body and attached with an “anchor” to the body of the fish. After that, the parasite’s swimming legs are reduced, as they lose their motor function.
The body segmentation also disappears.
The duration of a transformation cycle from an egg to a mature parasite can last up to days. The term of transformation depends on the ambient temperature.
Since lernias are heat-loving parasites, under aquarium conditions they can repeat the development cycle up to 12 times a year. One female Lernia is able to release up to 700 fertilized eggs to aquarium water.
And now try to imagine how many problems you will get with the active reproduction of the parasite in your aquarium.
As a result of penetration through the skin into the deeper layers of the body of fish and muscle, the parasite provokes the development of an inflammatory tissue process, which leads to the appearance of parasitic nodules. At this place there is a large ulcer in the form of an abscess. Bright or gray ulcers are sharply separated from healthy tissue.
Infectious disease is complicated by the occurrence of secondary infection or invasion (kosoz, saprolegniosis, etc.). In small aquarium fish, with its head part, the parasite can reach the abdominal part, where it penetrates the liver or intestines, which leads to the destruction of the internal organs.
It is possible to detect the parasite in the cyclops stage only if you look at the sick fish under a magnifying glass. Mature females hanging from ulcers on the body of the fish can be seen with the naked eye.
Treat fish in this way. Sick fish are put on a wet swab and the parasite is removed with a thin forceps, and the ulcer must be treated with a 0.1% solution of potassium permanganate.
As a preventive measure, you should ensure that no pathogens enter the tank with live food. If we consider that the parasite is extremely sensitive to the saltiness of water and it multiplies exclusively in freshwater bodies, water can be salted with sea salt (2 tablespoons per 10 liters of water), or boiling water – 1 table. spoon to 10 liters of water.