Fish do not normally "float around" they swim. If your fish is floating/sinking then it is probably dead.
The fish is either too full, or ill
If you overfeed a betta they will start to slow down their swimming and lay on the bottom.
The swim bladder
enables the fish to maintain its depth without floating upward or sinking.
Fish body is of boat shape to balance itself in the water nature have given swimming bladders for fish.
Not nessessarily. Bettas tend to get listless and lazy if you don't change their water often, and if they have no stimulation. Theres a great product out there called a Floating Betta Exercise Mirror that will make your betta think there is another betta in the tank. It can be used to stimulate the fish into more activity. You can find them online, at www.bigalsonline.com (product #25109).
nevermind, she died
If the fish is actually 'floating' rather than the fish has simply positioned itself at the surface of the water as they normally do there may well be something wrong. Check water quality daily and replace at least 10% every day if you want healthy fish.
It most likely means that he/she is sick because that is what happened to my betta fish. make sure you don't overfeed your betta fish because it can lead to constipation and that will cause trouble for the betta fish
it might be dead but if its moving tht means its alive and it has swim bladder disease
The white fins wont be moving and they will be at the bottom of the tank
other Betta fish and the bigger fish.