Epistylis is not parasitic, only an irritant where the stalk attaches to the fish's body. We had identified Neoichthyophthirius back in the 1980's but we didn't know what it was. We called it "hard ich".
Here are some excerpts from my fish disease book on these two topics:
Neoichthyophthirius
A similar disease has been identified in Russian literature. The journal that this disease was described in is not available in the English language. Using Google translate, some information was able to be extracted; They described the protozoan as Neoichthyophthirius schlotfeldti and it appears to produce a more coalescing, yellowish plaque on freshwater fishes. In that regard, it resembles more severe, end-stage ich. Under a microscope, the organism is rounded and its nucleus is so curved that it often closes back over itself like a ring. The trophont stage is 0.2 to 0.3 mm in diameter, as opposed to close to 1 mm in Ichthyophthirius multifiliis. The most important difference is that N. schlotfeldti does not produce a cyst stage. This means that development can take place entirely on the fish’s skin, and the “tank transfer method” will not work as a control method. Additionally, N. schlotfeldti reproduces well at water temperatures as high as 34 degrees C. (93 degrees F.) so heat treatment is ineffective in a range tolerated by almost all fish species. It can also reproduce at temperatures as low as 18 degrees C. (64 degrees F.) so lowering the water temperature only works as a treatment for cool water fish species. It is thought to have come into aquariums from southeast Asia. Treatment is expected to be the same as for other ciliate infections.
Epistylis
Cause
Epistylis is a non-parasitic, opportunistic stalked protozoan that can form white colonies on a freshwater fish’s body, especially at the site of a previous injury. It can take time to develop, and is rarely, if ever fatal, but unlike the similar-looking viral Lymphocystis, the lesions rarely go away without treatment. Lesions formed by Epistylis are rounder, and have less distinctive edges than Lymphocystis does.
Symptoms
Microscopically, Epistylis can be readily identified as a protozoan. In freshwater fish, early Saprolegnea fungal infections are sometimes misidentified as Epistylis, but fungal infections can easily be identified by taking a scraping and looking at it under a low powered microscope.
For unknown reasons, some marine fish may begin to produce excess mucus on their edges of their fins. These white lesions may also resemble Epistylis but will appear smoother, and under a microscope, a scraping will show only round mucus cells.
Treatment
While most freshwater anti-protozoan treatments will have some control over this protozoan, if the fish can tolerate it, a long-term dose with sea salt at 3 ppt seems to work the best. As with all salt treatments, using sea salt is best; it seems that the calcium in those products helps mitigate the sodium toxicity seen in some when plain sodium chloride is used. Additionally, always remember that you must increase the salt content of the water very slowly, over a period of days. Assuming the freshwater fish are salt tolerant, reaching the target of 3 ppt should take at least three, preferably six days. Reducing the salt content can be done quite a bit faster, in just a day or two. Salt tolerance of freshwater fish is not an exact science, but there are some general trends:
All brackish water species are of course highly tolerant.
African rift lake cichlids are relatively tolerant of sea salt (to around 4 ppt)
Goldfish and koi can tolerate salt at 3 ppt
Freshwater rays may be intolerant of salt higher than 2 ppt
Most Amazonian fishes do not tolerate salt well
Rainbowfishes generally tolerate salt well
Bass and most panfish are salt tolerant
It is vital that salt/salinity is measured very accurately. The margin of error between the treatment dose and a dose that is injurious to the fish is very small. Refractometers can be used to good effect, with the electronic ones giving the best result.
Jay
