i am sure they will love crickets, though they will have to come up to the surface to get them, so it might take a while. though tinfoils are more of a vegetation eating fish, so you might try offering some chopped spinach or romain lettuce. they are not too picky. i bought 2 tinfoils about an inch long and put them in my back pond about 5 months ago. i took them in for the cold weather, put them in my 110g. they are now about 7 inches. i believe they got big fast from eating insects and that good old pond algae. as soon as it gets warmer, i am gonna put them back out there.