This isn't really an emergency, nor disease treatment needed. So, unfortunately my beloved snowflake eel died from nose cancer, this was confirmed by an autopsy when my good vet friend found multiple tumors in his nostrils. He was also pretty young, over 7 years old (compared to my 21 year old and still alive). Because of this, my friend thinks that there are germs in my tank that could be promoting cancer. He suggested my tank to fallow for 3 months. However, I still have other fish in there such as wrasses and a trigger. The wrasses are IMPOSSIBLE to catch, especially with too many rocks for the eel. Fish traps are way too small for them, they are about a foot long per fish. I am left with the option of using a U.V. sterilizer. How long would I have to let it run before it is I add another eel in?