My Betta, which I have had for about 4 months now

is in a fresh water tank with about 16 other small freshwater fish (no other Betta's of course). Everything is fine with all of the fish and the water is fine . Today I noticed that he wasn't swimming around much like he usually does .. and didn't come up for food. He finally came out , but he is now swimming with his body at a slight diaginal slate .. with his head pointed downwards. He seems able to swim through the water .. but off balance. Any chance that this will clear up ? Or is he on his way out ? Thank you !

Swimbladder is a disease which symptoms cause fish to become unable to swim correctly, your fish may exibit swimming toward the bottom of your tank or bowl, then floating back up, swimming in circles or laying or floating on his side..

There are three main things according to the posts and articles I've read that can lead to swimbladder disease.

Constipation due to overfeeding

Bad water quality

Bacteria

I recommend the following regimine, recommened to me over two years ago.

First, as soon as you notice signs of swimbladder do a 50% water change, taking care not to stress the fish by having the water temp as close to his tank as possible.

After your water change you should not feed your fish any food for two days. On the third day feed your fish a fresh pea. Frozen peas thawed, popped out of the skin, and cut into bite size pieces. And then do another water change so that any uneaten peas do not contaminate your water.