I have 3 bubble-eyed goldfish in a 30 gallon tank. One of them is probably 2 years. His bubbles are about 1 3/4 inches in diameter. One of the bubbles is a little bigger than the other. Just recently he lays upside-down on the bottom for long periods of time. Sometimes hes swims upright. I at first didnt think anything of it because he has always swam upside-down on occasions but never layed like that at the bottom of the tank. I tried to flip him over and he goes a little while like that then hes back on his back. The others ones are fine. I dont think he is dying. Is it because of his big bubbles and the other being bigger? Should I pop them both to balance him again? Or is there something wrong with the tank. He has been in that tank for about 7 months now. Any help is welcome.