capturing something from the wild and then trying to keep it (especially when you do not know its requirements) could cause stress, injury or death to the animal, besides it just not being fair. I think it is OK to keep something for a day or two for personal interest and observation, but should be released.
I found a gray tree frog on the windshield of my car once so I set him up in a little tank, put in some fruit flies that I had for other herps, observed, identified him, then released him (2 days later) into similar conditions. I also rescued a spring peeper and a red eft. Again, I kept them overnight, then put them in out woods by the river.
Set him free to mate and carry on his species 
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Chameleon Help & Resource Info
0.1 Veiled - Luna
1.0 Beardie - Darwin
0.2 felines - Kyndra and Líta
1.0 African Clawed Frog - Skipper
0.3 Mad. Hissers (2 died ;(
0.1 Chilean Rose Hair Tarantula (no name yet)
0.1 Goliath Bird-Eater Tarantula - Natasha