I have a gold gourami that is laying at the bottom of the tank on his side. Sometimes he swims around upside down or twirling like he cannot keep straight. I have a 26 gallon tank with two dwarf gourami and a couple other fish I did a 25% water change and also changed the filter. After an hour he was the same and my snail was trying to crawl on him so I put him in a seperate tank. Any ideas whats going on ? anything else I can do? All the other fish are fine. I just added him to the tank a couple weeks ago.