I agree that your water parameters are probably out of whack. If you have all the fish listed in your aquarium info than your tank is very overstocked so getting your parameters in order will be extremely difficult, if not impossible. Since you just started the tank I would recommend doing daily 50% water changes to help your fish. The water changes should also help with the odor since that many fish will foul it up pretty quickly. If the 29 gallon you refer to in your signature is a real possibility than I would recommend getting it as soon as possible so you can move all your fish to that. A five gallon tank is suitable for a very limited number of fish as most either get too big, need more swim room, or produce too much waste. A single betta would be quite happy in a 5 gallon, if you can get your other fish moved. Good luck!
When I first started I put a small amount of raw salmon in and it smelled horribly the next day. Took it out and began using pure ammonium which worked much better for the smell. The bad smell (able to smell it in the room) went away the next day and the smell right next to the tank went away in a few days.