is a Alligator mississippiensis, if he/she has more than five years, is too small for that age.
You will need something bigger than a 125g , they can get 13'+(i keep one male of 15'6" in the Zoo). so if you want to keep it for life you will need an outdoor pond.
In the Basking area you need at least a fluorescent light that emits UV-A and UV-B wavelengths.(UV-B is important in the synthesis of vitamin D3, although they derive substantial vitamin D3 from many of their prey items which are part of a varied diet).
Feel free to ask anithing you want to know
Good luck, Carnivoro