I forgot you said it was a quarantine tank, my bad.
If you want to get a bit creative then that doesn’t necessarily stop you from putting shrimp in it and having it as a quarantine tank. You just let the shrimp breed upto about a hundred or two then transfer the majority of them to another tank. Obviously you would have put in lots of hiding places and whatnot in the other tank so the shrimp have a chance to reproduce. Now that that is done you have a colony that will remain stable in the other tank while the 5 gallon population can rebuild. If a quarantine fish kills/eats the shrimp then you have some you can move over.