Your fish could be bloated? Try feed it a pea. take the skin off and maybe cut it p to his mouth size. good luck!
The main thing you need to do is do some research. There is a lot you need to know to have a successful aquarium. There is such things as knowing the following:What size aquariumNitrogen CycleWhat fish are compatible with each otherHow often to feed your fishHow to clean your tankHow often to clean ouyr tankAnd there is much more.Take the time to learn about building and maintaining an aquarium before your start and you will be successful.
This depends. Here, this might help you a little bit.1 small fish (1-3 inches)A small bowl (Make sure you still have an filter!)2 small fishA two gallon tank3 small fishA two gallon tank4 small fishA three-four gallon tank5 small fishAt least a five gallon tank1 medium fish (2-3 inches)A two gallon tank2 medium fishA two gallon tank3 medium fishA two gallon tank4 meduim fishA two-three gallon tank5 meduim fishAt least a five gallon tank1 large fish (3-6 inches)A five gallon tank2 large fishA five-six gallon tank3 large fishA six-ten gallon tank4 large fishA six-ten gallon tank5 large fishA six-ten gallon tankAnd if your wanting a bunch of fish, here is a explanation.20+ small fish15 gallon tank20+medium10 gallon tankYou can imagine the rest.