That would be rather difficult. Bettas have many diffirent sub-species, including that of splendens. However, Splendens were breed, by humans, out of thier nature habit. Specifically, they were breed to be much, much more aggressive then bettas you find in the wild. So much so, that often times bettas aren't a wise choice to be housed with any other fish (As it may attack/harras it to death).
Of course this diffirs from betta-to-betta, as there are Owners that DO house other fish with bettas without any negative results. As far as actually natural fish found with that of the bettas in the wild, I'm uncertain. Again though, having a fish from 'its' natural habitat will not mean that it will get along with it (To believe this may be blantanly ignorant).
IF you do still decide to house other fish in your aquarium with the betta, the most sure-footed way to do so is research, research and more research of the choice fish. For instance, since the betta fish is natural territorial and agressive, it may be best not to house it with other such fish, and instead find peaceful bottom feeeders (not necessarily always fish, it may be a snail or ghost shrimp, etc.).
Secondly, the choice fish must also be well suited for the tanks adjusted environment; as in, if you thought of getting a gold fish, this would be an unwise idea for goldfish thrive in cold temp waters, and often prefer diffirent variables in water chemicals.
If the choice fish passes these first to requirements, then think of the future of that fish. If you're thinking of getting a pleco fish (Sucker fishes) then take into consideration of how large this fish will eventually get. While most plecos are sold at stores at thier younge stages (consequently also their very small stages) they do grow -quit- large. In most cases, where they start out 3-4 inches, they will sometimes grow up to a foot long!
It just breaks down to research =/ Heres a shortened list of what to match your 'choice' housing fish against.
='Choice Fish' Requirements List=
1) RESEARCH - Theres never 'to much research'
2) 'Common' Personality of Choice Fish
3) Required environment of Choice Fish
4) Future of Choice Fish
- I have no suggestions, others will tell you to not get "Fish A" and others will tell you that "Fish A works perfectly fine". The BEST, and most IMPORTANT of all, is that you HIGHLY emphasize practical and responsible caretaking! If you see that your fish does not get along at all with the betta, then return it to the fish store, or place it in a seperate tank!
Note: Although, to give you an idea of what you might be able to add, here is a list of some things that I have seen others try.
-Guppies, Ghost Shrimp, Mystery Snails, Cichlids, Cherry Shrimp, Neon Tetras, 'Glofish', Plecos. There are more I'm sure.