Censorship of adult words to a child is not part of America's problems. Its good morals!!! I am glad I can be on here and not worry about my kids being around and reading offensive words in a post. Thank you to the moderators and staff here at the tank!!!!!!!! I was one of the first to read this post and almost suggested he look into a swim bladder problem. I only have 33 years into keeping fish and have only had a few cases of this myself (yes, due to crummy water by inexperience at the time) so i left it along due to my inexperience of this problem. From the facts posted it points directly to swim bladder problems but, there are many cause besides bad water conditions. Constipation for instance can cause the intestine to be enlarged and press against the swim bladder, temperatures to low for the fish can slow down the metabolism causing constipation. Parasites and infections can also cause swim bladder problems due to inflammation. It sounds like the water quality is not an issue,, he has plenty of filter on it. Sounds like he is doing water changes so he can keep on top of the overstocking issue, water changes twice a week would be recommended by my opinion. This is from very limited knowledge on swim bladder problems. Also, Old Vet, Can I ask what the other advice was?? This old dog is always wanting to learn new tricks!!! My inexperience can always use a new lesson.