My main issue with Uronema is that it is so common when people treat with low salinity.
Here is an excerpt from my Advanced marine Aquarium Techniques book:
Hyposmostic therapy for marine fish disease treatment:
This is the much touted “low salinity treatment” for the marine protozoan fish parasite Cryptocaryon irritans. The basic premise is that most marine fish can tolerate a lower salt level than can this protozoan parasite. Reducing the specific gravity of the aquarium the proper amount for an adequate length of time does often eliminate active infections of C. irritans. Generally, this means maintaining the fish at a specific gravity fully half that of normal seawater (1.0125) for 14 to 20 days. The difficulties show up when aquarists modify the treatment due to extenuating circumstances. For example, since not all fish can tolerate that low of a specific gravity, some aquarists try the treatment at a slightly higher specific gravity (say 1.016) for a longer period (30+ days). This should never be attempted. There is a particularly virulent protozoan named Uronema sp. that thrives in brackish water. Given enough time, it very often infects the fish and is very difficult to treat. The symptoms of Uronema mimic that of an external bacterial infection (open red sores, scales falling off, cloudy fins). Even the most experienced aquarist will usually misdiagnose an Uronema infection unless they have access to a microscope and look for the protozoan with that device. There are other anti-protozoan treatments that are less risky and much more effective than this treatment. Remember, while the salinity of an aquarium housing marine fish can be reduced almost instantaneously, raising the salt level back to normal values at the conclusion of the treatment must be done very slowly – even over a period of three or four days.
Prevention seems to be the best course of action, as this protozoan can go intercellular and then is almost impossible to eradicate (IMO).
(Although in one In one case, formalin and DMSO was applied to a weedy seadragon infected by a serious sub-dermal Uronema infection, and it was eventually cured with no lasting side effects.)
I've also used formalin or high dose copper treatment (0.23ppm) to treat for it.
The John G. Shedd Aquarium in Chicago has informally reported on a technique that holds some potential for testing an aquarium for non-obligate parasites such as Uronema; simply suspend a whole, (previously frozen) smelt in the tank for 12 to 24 hours, then remove it and search for the presence of these facultative parasites.
My I.D. of "Uronema" in these cases is provisional, it is basically a moderately mobile generic protozoan that we've always called "Uronema".
Jay
