Betta fish doing terrible

Question
I'm sure my betta fish is about to die. He lost all his color his fins look awful and frayed, he won't eat and he just stays at the top of the tank (almost vertical now), he is breathing very slowly and does not swim. He's in a large 5 gal tank which we changed about every two weeks. I thought it was that dropsy but he does not have an enlarged stomach near the front but maybe I just can't tell. We asked the fish people at petco and they said we overfed him and he probably will die. We said we followed the directions on the container and they said yeah that brand TopFin is made by Petco, Petco killed your fish. It tells you to feed 3-4 pellets twice a day. Which from what I've now read is about twice what we should feed. So unfortunatly gills won't last. My question is do you think it was anything else besides overfeeding, do you think it is dropsy. We plan to get a new one and care for it properly. How do we sanitize everything for the new fish? I figured just run it through the dishwasher or wash with dish soap. Thanks for your help.

Answer
Well, it is definitely NOT overfeeding.

It is swim bladder disease, caused by poor water quality, mal nutrition and partly genetic defects. You can not just feed one food, you must feed a variety for proper nutrition. Also, TopFin is one of the worst varieties out there.

There isn't a lot of chance of saving your fish. Feed shelled peas if he will eat them, add a tablespoon of aquarium salt and increase water changes.

For the next fish, step up to weekly water changes, and switch to a better food. All pet stores should carry a product called "Hikari Betta Bio-Gold" Or "Hikari Betta Gold". That stuff is the best staple for your betta you can get. Even that isn't enough though. You will also need to give him freeze-dried Bloodworms. All pet stores should sell this, just look for it near the foods.

I wouldn't run it through the dishwasher, it could ruin the seals.

Just give it a good scrub in warm water with dish soap like you said. And make sure to rinse it like crazy, if any soap is left on it will kill your fish.

-Nick