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.
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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