wild betta tank??

Most Betta species aren't hyper-aggressive with their own kind. The fighting spirit in commonly available Bettas is definitely enhanced by selective breeding. There are so many different species of Betta out there with different requirements. Some build bubblenests, some are mouthbrooders. VERY generally speaking if you give them a well planted 10 gal tank where they're either the only species or definitely the focus of the tank with no annoying tankmates you can keep a pair or trio no problem. With more specific info about exactly what species you're interested in you can get more specific info on how to keep them. Suitable tankmates would vary with the species of Betta, but generally as long as it can't be swallowed, isn't a hyperactive chaser or just downright aggressive it could work. But some Betta species would be more shy with other fish swimming around. Think about Microrasboras, small Tetras like Neons or Cardinals, Corys, and Otos for a start.

I have a 15g that I originally had set up as a SE Asian Biotope for a pair of B. pugnax and a group of 7 harlequin rasboras. I didn't get to see the interaction between the pair of pugnax because my male died after he contracted a bacterial infection that killed off everying in that tank except for 1 harly, so I can't give you too much info about it.

Can you take pictures of them? There are many groups of bettas that require very different care. Some live in quiet, acidic ponds, while others come from alkaline streams (they're much bigger. 10g is usually a large enough tank for most wild bettas.

Betta smaragdina are easy to find, but probably need a 20 gallon tank. Appropriate bubblenesters include Betta coccina, channoides, albimarginata, brownorum, livida, imbellis, miniopinna, and persephone.

Mouthbrooders suitable for a 10 gallon would be Betta picta, fusca, dimidiata, pallida, pinguis, prima, pugnax, pulchra, raja, and rubra.

Mouthbrooders will be much harder to find.