Hey,
I Have been working with a few crocodilian species for awhile now (nile crocs, american alligators, spectacaled caimans and dwarf caimans) And with my expierience a crocodilian specie should be started off in no less then a 6 foot by 3 foot encolsure, about 3 quatres of that cage should be water. Yet I found for certain species when babys you can pull off something smaller. For intance since caimans are quite secretive you could keep them in maybe a 4 foot by 2 foot cage while young, if this cage is sheltered welll. Also I have a new baby american alligator who is about a foot and a half long, she is an extremely laid back animal (except for when being fed lol) and shes being comfortably kept in a 108 gallon aquarium (6 foot by 1.5 foot_
I hope this has helped you out, email me with any further questions ( reticulatus_jay@hotmail.com)
JM