he's not sick with swim bladder... the swim bladder is an organ that helps them maneuver up and down in the water, not a disease. what you're thinking of swim bladder disorder. this simply refers to something that is effecting the swim bladder, not one particular problem.
there are a few causes of SBD:
1. constipation. stop feeding for 3 days. on the 3rd day feed a bite sized piece of the inside of a pea. don't feed for another day. if this works, start feeding a little less and every other day.
2. internal infection or parasites. these two are almost impossible to tell apart. change 50% of the water (assuming he's in a proper, filtered and heated aquarium) and start feeding medicated food. they should have a mix of parasite and bacterial food, but if not get both.
3. injury of defect. fish can be born with deformed swim bladders, or rough handling can lead to injury of the swim bladder. if you've recently tried to net him, or he jumped out of the tank or anything, he may have injured his swim bladder. if this is the case, it just needs time to heal. it might never heal, but he's not in pain so there is no need to "put him down"
good luck...
also, he'll have a much better chance of getting better if he's in a filtered, heated tank of at least 2.5gallons, so if he's not I'd suggest getting one.
