Why would a male Betta fish float straight up and down also fins are disappearing?

Its water is not being looked after properly. The poor fishes water must be absolutely putrid for this to be happening. Please change the water ASAP. Then if you follow the basic rules of sucessfull fishkeeping, and mend your lazy ways, your fish just may survive your shockingly bad treatment of it. The basic rules are. "1 inch of fish needs at least 1 gallon of water. (a Betta is a 3 inch fish) Every tank must have a permanently running cycled filter. Every tank must have at least 50% of its water replaced every week."