I'll throw in my two cents since I have some experience with feeding fish.... to snakes that is,lol. I have a ribbon snake (more or less a garter) and it eats fish, mainly rosy minnows, but occassionaly goldfish when the pet store is out of the minnows. A "goldfish only" diet will lead to poor nurtrition and the thelamine (spelling) problems...for gaters and ribbons they are fine occassionally, for a corn....NO! Don't feed corns any fish, no point in doing it, they don't have the value that they need even if they would eat it. And of the clumsy baby corns I have had, I would love to see one jump in the dish to try to even catch it, lol. Rats are best nutritional value, but I can't get any of my corns to eat them, they'll eat only mice. Chicks and finches are fine to feed to corns, but let me warn you of the poop smell!! There aint nothing like a pile of crap that used to be a bird that came outta a large snake!! He is eating mice, let him eat mice....you may end up causing a problem if he eats a chick and then decides that is all he will eat. I have that problem with a russian rat snake, was eating medium rats, I gave him some mice one day because I didn't have any rats and didn't want to run the 30 miles to where I can get frozen rats locally. He won't eat another rat since! turns up his nose, even when left all night with it and after not eating 4 weeks....so now I am at the place of feeding 3 or 4 mice to him to equal the rat that he should be eating! Mice are working, stick with them, try rats if you can for the added value, but if he won't eat them, stick with mice before you end up with a headache.