Call me a bad owner but I'm saving to buy them nice things and I don't want to spend a bunch on food. Sorry if it's a stupid question, I'm new and still figuring everything out. ^^;
Pop them into the resort, on veta lake. It's 1400 for 14 days, and you can set an alert so you know when to put them back in. here
I keep mine in the resort as well. They stay fed and happy for as long as you keep them there.
As long as you choose just the basic package at the resort it's really cheap. 100sp per day.