Partial tank crash

[jarrid]

I would have to agree w the oxygen depletion theory, because once I turned the skimmer back on then thats when the remaining trigger stopped breathing so hard and fast. The skimmer is a hang on back and has an overdraw tube coming from the cup and it was going crazy overflowing back into the tank until I did the water change. So how should I medicate then ?? Should I isolate The sick fish in a bucket and do a drip ?? Or leave the skimmer and uv light on And medicate directly into the tank ??