[Aaron]

This will totally work. Wild Bettas, especially in the splendens (imbellis, mahachai, bellica, smaragdina)group will do well in an appropriate community. Rasboras make good companions, some barbs too. I'd stay away from danios and other active fish though. Lots of plants and some floating cover will make them happy, also keep the current to a minimum. Your tank can probably accomodate more than one trio, I keep smaragdina and imbellis in 15 gallons (2 pairs in each) and the males seem to have enough room for their own territories.

Although harder to obtain, many of the mouthbrooding types would also be perfect candidates for such a tank. I actually have a tank with four different sp. (dimidiata, channoides, sp. Kapuas, and livida- not a mouth brooder) in one tank. This was not by choice and it was to be only temporary, but it has been several months and all is well. Even some spawnings! The tank has plants, but not really scaped, but they're happy. Theres a small school of Rasbora pauciperforata to keep everyone out and about.

 

[Aaron]

I never got to work with Rhombo barbs but I always did. I have only seen them once years back and they were pretty awesome. I have kept hexazona whish is supposed to be pretty close and they were really shy, retiring fish (I guess like you Rhombos)Where did you find them? Where are getting the Mahachai from? Wild fish? thats another I'd like to keep sometime (the only one of the four I have not kept). It's gotta be the nicest of the splendens group.

The bettas you see in cups in the LFS are so far removed from wild fish, it is incredible. Wild Bettas are social, almost gregarious, and very much territorial. In a group, fish will establish a hierarchy where the alpha male will get the best digs and show the nicest color and finnage. This is not unlike how colonies of Apistos work. Some West African Killies might be a better parallel.
IME, fish brought up in groups will result in very minimal agression. Once cupped and separated, males AND females will tend to get a bit more feisty. A wild fish from this group however will not come close to the aggression of domesticated ones.

 

[Aaron]

Carlos,
A pair or trio of the splendens group should give you no problems in a 5g cube. I kept a trio of smaragdina in an eclipse six and got a couple of spawns out of them. just be sure to give them enough refuges when the male gets too rough. (This will happen from time to time when the females are not in the mood.)
I have a little experience with the coccina group (currently keeping coccina, livida and sp. Palangkunbun) and from my observations, seem to be more intolerant of each other in smaller tanks. Both coccina and livida, I found will do well in groups only if kept in a 15g, they just need more space. Males and females are equally territorial and will bully each other to death if not given enough buffer. My sp. Palangkunbun are too very feisty, but it seems they are just nippy and like to tear each others fins rather than bum rush each other in their mid-bodied spots. This group is really secretive, so you might not get the same kind of satisfaction in watching behavior, I have to sneak up on my fish and hide behind a shield to observe them well!

The mouthbrooding types are by far the most gregarious and tame of the genus. They also have the most intriguing spawning rituals I have ever witnessed. I bet a pair or trio of dimidiata could fit in a 5g cube, even a pair or trio of albimarginata or channoides. Be prepared to drop some serious cash though on the latter two.

 

[Aaron]

I just wanted to share some of my bettas that I've been keeping. The pics are not very good, but it is the best I can do as I am shooting them as is in their breeding tanks and they hate the camera. the water is stained from leaves.

Betta livida, female

Betta foerschi, male

Betta burdigalla?, male eating a worm