Ive been doing some reaserch on what type of fish, aand i found the neon tetras arnt the best choice since they are a school fish and theres not much water there, i was thinking white cloud minows or a betta.
You should check online, and if worse comes to worse order some eggs and try hatching them. I dont have any experience, i just been wanting them for the past 3 years lol, just never came around to getting them yet.
Nice pics of your new terrarium, of course is your final desicion what kind of fish you will put in the aquarium zone, but my suggest would be that if you are thinking recreate an enviroment like South American rainforrest,
you would have to add fishes from our region too
If you don't have enough filtration for the aquarium zone, forget the tetras, I think the best choice (in S.A. fish) would be a couple of Killies like Pterolebias or Cynolebias or even Rivulus, they will feel like in home