I really think you need an ID to ensure proper care, but if you are able to provide adequate care and supply a safe adequate environment, then all is dandy.
Having a menagery of different reptiles invertebrates and others, i kind of feel a little bothered by the fact that it was considered a short term pet. Its nothing to do with me but i do hope this doesnt result in the animal being put down down the line, thats my only concern here as i know what zoos are like.
I have had to rehome African rock pythons, Retics, anacondas, nile monitors and other large powerful reps for the exact reason of it being a short term pet (Until its too big to care for) Its not an easy task!
If people are going to get something like a crocadilian, then they NEED to reseearch it and consider long term care, if you cant provide it down the line, then you should ensure that someone else can or just dont bother in the first place, its not fair on the animal.
Once that caiman grows up, itl need a space bigger than a tank can provide itl need a space bigger than the average bedroom. Itl need lots of light, heat, heated water, food, insurance and many other financial considerations. Its a big undertaking , i hope you have a plan of action and can ensure its wellbeing in the long term.
NB: As above, try RFUK, there are many croc owners on there that will be more than willing to provide ID, care and any other information you could possibly desire.