I know this will sound strange. I have three small orandas and one medium fantail in a well established (2 years old) tank. I keep the water clean, they have always been healthy. The other day the tank water was getting low and the filter started making noise. I didn't want to burn out the pump, but I was late for work, so I shut it off. I planned on topping off the tank and turning it back on, but then had to work two really late nights. So, the pump has been off for three days. Today, as I topped off the tank I noticed that all four fish were all at the surface, which they don't usually do. Also, they each had a circular white circular bump on the center of the top of their head. Same size and location on each fish. Once the tank was full and the pump back on, they resumed normal swimming and eating etc. They seem fine. As of a few minutes ago, the white bump is gone from two of them, still present on one (but seems better) and worse on the fourth one. I have had fish for 20 years, including my salt water tank, and am familiar with most fish skin problems. This just seems so odd. Could shutting off the pump lower the oxygen in the water, thus driving them to the surface for air, and the part of their heads that was exposed to the air turn white???
