Bloated Beta Fish

Question
We have had a bloated beta fish for a while and now he is on the bottom of the tank and is not moving much.  

Answer
This is probably due to poor water conditions. Buy pH, nitrite and ammonia test kits. The nitrite and ammonia should both be 0.0, but if the tank is not filtered or cycled, it is probably over that.
Do regular 30 percent water changes to get the nitrite and ammonia down to 0.0. I hope the tank is filtered and heated effectively. If not you need to buy a heater and a filter for it. I also assume the tank is over 5 UK gallons (7 US gallons). They need at least this amount of space to live happily.
When all these requirements are met, he should be more active, and not bloated any more.
Good luck,
Kathryn