sick black suckerfish

Question
we have a 10 gallon tank and we had 4 small goldfish and the suckerfish started acting sick would lay on his side and sometimes would jump to the top of the tank as if he was trying to get air. we took two of the biggest golds out and cleaned the filter and he came back to life as if he were better 1 week later we saw him jump to the top of the water several times and sink to the bottom again laying on his back. we cant figure out what could be wrong with him please help thankyou!!!!!

Answer
Hi,
You'll need a bigger tank for all those fish. I also needd to know what type of fish exactly it is, as I can think of 27 types of black suckerfish of the top of my head. The problem is a combination of stress and water quality. Keep up water changes of 25% two times a week for that tank.