I have 3 common goldfish in a 30g aquarium. They are about 2-3 inches and ammonia is always 0, nitrite always 0, and nitrate around 20 or below. I do 25% water changes once a week with Prime as my declorinator. However I know this is too small of a tank for them so I just recently got a 55g. However I am moving in about 3-4 months and figured it would be less stressful and easier to just set up the tank then and transfer them to the new place. I also don't trust the apt complex I live in right now as I have seen termite dust multiple times. I pointed it out to them and they didn't do anything about it. I really don't think the structure will support 600+ pounds of water and rocks (I'm also in the 2nd story) so I'm waiting till I move. However recently they have been gasping at the surface a lot, more specifically after eating. I feed Omega One sinking pellets. My first thought was ammonia and as I was testing it I broke my last glass vial. I ordered more but I can't test my water until they show up. My ammonia is always at 0 tho. I have an extra air stone in the tank and I lowered the water level a little bit to make the filter create more surface agitation for better oxygen exchange. Any other suggestions that can help them stop gasping?