my male fish is realy fat

He's fat because he eats a lot. He's red because he's embarrassed about being fat.

Perhaps if you really want a straight answer you should start out by telling us what type of fish you have...or what it looks like...size...shape...other physical characteristics. Some of us are topical fish fanciers so we can help you.

How do you know it's a male? If you bought it from a tropical fish store, what did they say about it?

Here's a link (click on it) for identrifying fresh-water aquarium fish:

http://en.wikipedia.org/wiki/List_of_freshwater_aquarium_fish_species