There are 52 species of flagellates in the genus Cryptobia, a genus belonging to the class of Kinetoplastea. Most of these flagellates are not parasitic to fish. However, the few pathogenic Cryptobia species parasitizing on the skin, gills, intestines, internal organs and circulatory system of freshwater and marine fish species are of great concern in aquaculture as they can be dangerous and deadly to fish. Advanced symptoms are white stringy feces, pop-eye, holes in the head and bloating. Frequent fish deaths in the aquarium is an indicative sign as well.
Сryptobia iubilans is the only known representative to be found in the intestines of freshwater fish. In contrast to Spironucleus sp., Cryptobia iubilans has only 2 flagella extending from the front end of the cell, but because one flagellum is directed along the cell backwards it looks as if one comes out of the front and one comes out of the back. The appearance of Сryptobia iubilans resembles a mouse, with a pointed nose and tail.
Infection with Сryptobia iubilans occurs directly (without the need for intermediate hosts) through water, feces, and by eating fish carcasses. Once inside the intestines of fish, the number of parasites increases. As the population of parasites in the intestine goes up, the fish may show inflammation, accompanied by abundant mucus secretion and the appearance of long, translucent or whitish feces. In later stages of the infection, the fish develops granulomatous gastritis when granulomas can be observed forming in the intestinal wall that look like mycobacterial granulomas (Ziehl–Neelsen staining can help to establish the origin of the granulomas, whether it is bacterial or parasitic). Granulomatous gastritis and gastroenteritis, accompanied by an inflammation of the mucous membrane of the stomach and intestines, leads to an impaired digestive and absorptive function of the digestive tract. Сryptobia iubilans can cause the development of extensive necrotic changes in the parenchyma of the liver and spleen. General pathological examination reveals hemorrhages, intestinal necrosis and edema of the stomach wall, and microscopic examination reveals a large number of Сryptobia iubilans in the intestinal submucosa and in the liver. Infected fish stop feeding, often stay near the surface or the bottom of the aquarium, movements are slow. The appearance is edematous, unilateral or bilateral exophthalmia (pop-eye) and abdominal ascites (bloating) may occur. Due to the disruption of the intestinal function, the body does not receive enough nutrients. This is one of the reasons for the formation of erosions on the head and body – and a symptom of hole-in-the-head disease. One by one, the fish die. Infection caused by Сryptobia iubilans is most commonly seen in cichlids such as Apistogramma, Astronotus, Cichlozoma, Discus, Geophagus, Angelfish and others.
So far, no treatment against cryptobiosis is known to eradicate the parasite completely, however eSHa HEXAMITA will reduce the number of parasites, prevents mass mortality and enables fish and their immune system to recover and cope with this parasite. Normally, fish live perfectly well with a low amount of Cryptobia.
