betta fishs swollen and bloated belly

Question
I need to know why my betta fish has became bloated so big that he is now transparent in his belly area. I have only been feeding him TetraMin
tropical granules and I do not have a heater in the tank although the light keeps the water warm and there is also alot of black stuff that keeps coming back on the plants and the side of the tank.  I am not sure if it is algae or not. I was feeding him flakes until about three weeks ago when I ran out and his belly has expanded a noticeable amount in the last couple of days. Can you please help me? I don't want him to die.

Answer
hi, In that case what you could do is limit the feeding. You should only feed the fish 2 times a day. Also when you putting a food, make sure his eaten all. Don't put too much, this could make your fish sick. Also take a time to clean a tank every week, change about 20-25% of the water,
clean the alage in the tank and clean the gravel using gravel cleaner. If the problem get wrost let me know..


hope i helped..