Why are my fish still gasping for air?

So I have two fancy goldfish and one koi fish. I have had the koi fish and the fantail goldfish the longest, and the third fish is an oranda goldfish. So for a while my two fancy goldfish would go up to the tank and make bubbles. At first I thought it was cute until I did some research and found out that that means they are suffocating and need more oxygen in their tank. So I bought a air pump and thought that they would stop but, they haven’t. If anything I think they do it more now then they did before. Also before I installed the air pump into the tank I never had a algae problem and now I do. Algae is now growing in my tank and I need to know how to stop it growing and to prevent it from coming back. Another thing I should add is my oranda goldfish has swim bladder disease. I’m a little nervous because the previous oranda goldfish I had had the disease and he sadly passed away, and I don’t want the same thing to happen to this one. I read online that giving peas helps them, and acts kind of like a laxative for the fish. I was wondering is there anything else I could do to help my fish? And about the algae I have a 10 gallon tank with three fish and I was thinking about adding a algae eating fish to help keep the tank clean longer and to remove the algae. I know my tank is small and I should have a bigger tank but I don’t have the money to buy a bigger tank. I know that Petco has their dollar per gallon sale and I desperately need that so I can make my fish happy. Does anyone know when that sale is coming up? And should I buy the algae eating fish now, or wait until I get a bigger tank? And can someone please explain to me why my fish keep gasping for air, even though I have a air pump for the tank.

Sorry I started to ramble a little but I’m just a worried pet owner who is trying to keep their pets safe and healthy.