Was he the first up for the food every time?
We did have two fish, both in the same tank, but John's Mom managed to overfeed them by giving them almost a whole container of food in a week when we were on holiday some years ago. The other one died but it had no effect on Freddie.
I moan about him but I'm quite attached to him really and always shout 'Goodnight Fred' when I turn the kitchen lights off at night, and 'Morning Fred' in a morning