My 6in. tiger oscar has not eaten in 4 days. He is swimming around very slowly ignoring everything. He also spends alot of time up top by heater and filter output. Today I noticed a sore on his chin and a sore on his chest buy his gills. They are covered in a thick white cotton fuzz. I would think that they were a scrape or something if he were acting okay or the sores weren`t white and fuzzy. Water tests are: 0-.25ppm ammonia,o nitrites,2o nitrates,6.0 ph. Any ideas?

If the sores are white and fuzzy i'd say it's a fungal infection.
Could we see a picture?
Does your ammonia always test like that?
It should be zero...

Noddy wrote:

i concur with Noddy.... a picture will help us evaluate
the situation.... and i suggest water change while waiting
the input of other....

I cannot get a good pic but I will keep trying. I changed filters 3 weeks ago and even with old media in new filter I am getting trace amounts of ammonia. I am doing water changes every three days. It takes that long to build up. Also the color on the test kit is between yellow and yellow green. Would you go ahead and treat for fungus?