I have a male betta, I've had him for a few months now, and he's been healthy. About 4 days ago, he wasn't eating much, and he would float near the top in one of the corners of the tank. I immediately called one of the fish stores located here in town. I took him down within the hour. The guy told me he looked fine, asked me questions about what I was feeding him (Nutrafin Max), he gave me Omega One Betta Pellets, my fish won't eat them, but when I put the flakes in the tank he goes right for them. He also gave me Betta Revive to put in his tank for a few days, and told me to switch to spring water. I did all of which he asked me too, and my fish seems to be okay. But I did mention another behaviour to the guy and he told me it might be a parasite. He swims quickly to the top he arches his body in a relaxed u shape, and then proceeds to stick his mouth in and out of the water while travelling around his tank. It's hard to describe. It reminds me of a dolphin in an odd way. I have a 1 gallon tank, with an undergravel filter, and an airstone, so theres bubbles floating around on the top, maybe he's chasing them? I have no clue as to what he's doing and if it's natural for him to do or if he is sick. He's been doing it since a day or two after being in his tank. Is this normal for him to be doing?
Sorry for the lengthy post.