Miles;1116859; said:Change the water..
Add an ammonia detoxifier..
Find some cycled bio-media and add that to the filtration.
If his 100g is 'cycled better', throw that filter on the existing tank in addition with it's current filter.
What size was the tank the ray was in?
The #1 problem I keep seeing is people under-estimating the bio-load of stingrays. People will buy juvenile rays and be told its 'okay' to keep them short term in tanks of less than 125g, because the ray is small and dosn't need the swimming space. Even if the ray has swimming space, they need a huge amount of water volume to dilute waste levels.. as well as diligent maintenance and water changes, and adequate cycled filtration.
IT is better now. He did just as you said. THe tank is a 100 gallon bow front. I agree totally that a tank of even that size will be hard to keep even a juvenile ray in without serious water changes and filtration. Thanks for everybody's help.