I have for years used guppies for my baby and young turtles and for the adults I use swordtails because they breed easy and are simple to sex. What you do is set up a 10 gallon tank and get 2 males and 5 females and in about 2/3 months you should have a colony of feeders. I tried the guppys with my new dwarf caimen but am unsure if he has eaten any and soon as I have a new batch of sword tails I will try those and post how well it works.