When fish suddenly exhibit symptoms of stress, here's the list of things to do:
1. Check the temperature.
2. Check the nitrite level.
3. Check the pH is stable (the precise value doesn't matter in most freshwater tanks, but stability is important).
4. Look for anything odd in the tank: dead fish, or something children might have dropped in.
5. Replace 25-50% of the water.
6. Consider if anything in the environment might be toxic: paint fumes, bug spray, etc.
As a stop-gap measure, change some water and increase water circulation. Adding extra aeration helps. The idea is to optimise conditions. Don't feed the fish. Plecs are generally very hardy animals, but certain things, such as sudden changes in pH, will cause severe stress. A few medications (particularly those containing copper and/or formalin) can stress certain catfish species. This isn't consistently reported, but has been noted by some.
Cheers, Neale
Woke up this morning to find my common plec lying on his back, hes still breathing. Ive had him 2 years with no problems. I do regular water tests n paramaters are all fine. His stomach is sunken but hes not starved. He tried swimming at one point but couldnt very well, he was spinning (around the length of his body axis). He has never suffered illness or disease. Can any one suggest anything?? Its been 7 hours since we noticed and hes still alive. Does he have a chance?? i dont want to lose him