Thanks everyone for your thoughts.
I have a one gallon tank with a filter.
I don't know much about what cycling means? I siphon out the poop every day or so with a straw and suction, and then change the water every 3 weeks. I watch while he eats and take out the uneaten food before it sinks. I use spring water for him because I don't think our water here is that great. He has marbles on the bottom so I don't know how to clean them other then dumping all of the water out??
No worries, my niece only visits about twice a year since she lives about 6 hours away, and she know next time she just has to watch. We have a cat who she adores so she can just feed him!
I don't think he ate any of the food when she dumped it in-he seemed to be in a daze because it looked like one of the snow globes when you shake it up-the pellets were floating throughout the tank! There was no way I could get all of those pellets out without dumping the tank-it would've taken hours and all I could think was that I had to get him out before the excess food made the water quality horrible.
Two days later and he seems back to normal. He loves his new food so that seems like a good sign. He hasn't made as many bubble nests as usual, but I'm sure the whole event stressed him out.