So I came home from work today to discover that my blue VT was gasping for air at the top or his tank. I tested my water, everything was normal, but I did a 30% WC anyways. He's still gasping. He stays at the surface with his mouth sticking out of the water. When he gasps it's making a squeaking noise? The temp outside last night got to about -17°, and my tank went from 80 to about 71 or 72°. I added another heater and brou h t it back up to 80. What could be wrong with him??