I just went go feed my puffer. Usually, he gets a little excited when I go near the tank, and immediately starts searching for food. Usually, when I approach the tank, he is unsure and will usually back off for a second. However, tonight when I fed him his food, he went right past it, and just swam right into the wall. Every bit of the food got sucked up the filter, and he was still buzzing around past food. I remember him doing this once before. Could he be blind? I really don't know what to think right now, but I'm a little worried.