Identifying ciliates is tough for me. When I say "Uronema" I'm really saying "Uronema-like". If I isolate a ciliate from the muscle tissue of a fish, then I'll be more sure of its ID. That said, these seem too motile to me.
Uronema is ubiquitous - it is found in most mature aquariums if you look hard enough. I've hung dead smelt in a tank and gotten Uronema on it the next day in many tanks. Uronema normally feeds on bacteria, it only becomes a fish pathogen under certain circumstances; particular species (Green chromis, yellow wrasse, anthias, etc.) and usually when you first get them. Uronema infections also show up during hyposalinity treatments. Otherwise, I don't recall ever seeing an infection from them in an established tank.
Jay
