So my betta is acting very strangely. I'm not sure what's going on so I'll just give you as many symptoms as I can. He will go through periods where he will sit in a corner or against a leaf in his tank. maybe he's trying to steady himself? Then he'll burst out flicking his tail really quickly, doing a lap around the top of the tank and stop. He float on his side from time to time. While he is at the top he is breaching the water for a good amount of the time that he is there. His stomach seems bloated to me and his gills are sticking out. His scales don't seem to be popping out nor do his eyes. His fins look almost perfect. He has a gallon tank with a filter, however I don't turn the filter on frequently because it seems to scare him. In the tank he has a fake plant and a rock. His tank was cleaned two days ago, no soap or anything weird like that was used. The temperature is luke warm right now and he has a light on. I turn the lights off when it gets dark outside. I got him a week ago for my birthday, but I think my girlfriend who gave me the fish might have over fed him while she had him because there was a lot of food laying on the floor of the aquarium. The tank was mercury before I changed the water because of the food I believe. He has not eaten much since I got him, and would not eat at all until I changed the water. The attached picture is him, Galileo, on the of the tank change. Thank you for your time and help.