I have 3 orandas and one black moor in my tank. One of the orandas eats the most. Whenever I drop the food in the tank, this one will gulp 3 to 4 pallets at once while the others pick one at a time. As a result this one fish out of four is like twice the size of the others. Its belly is round like a balloon. This fish is very jumpy. It dashes around the tank a lot as if it is escaping an attack.

This afternoon, after I fed them, this oranda was dashing around as usually. I didn't see what actually happened. The next time I looked, it was lying on the bottom belly up. I reached in and try to check if it is dead. It came to again as soon as I touched it. It swam around slowly as if it just woke up and dazed.

I don't know if bumped itself into a decoration and got a concussion when it dashes around like crazy. Or if it got an heart attack during its dash because it is so obese. I didn't see the whole thing happened, so I really don't know.

Has this kind of drop dead episode even been recorded? What could be the explanation?

Please comment, speculate.