try marbled crayfish or marmorkrebs. They are manmade and self cloning(no males in the species). You just start with one and a few months later are rewarded by 50+ 1-2" young. If you were to let a few of thos live long enough to reproduce, then you have yourself a colony/never ending supply in around a year.
just one condition DON"T LET IT GET OUT
What size tank would you recommend using for this? Could I do it in a 10 or a 20g? And do substrate/fake plants/hiding places matter at all?