Join Date: Oct 2010
Location: Victoria, Australia
When it comes to this complex, I don't know how high the risk of hybridisation is, but it's always possibility when keeping two closely related species in the same tank.
There is also the issue of aggression, especially if one or both pairs spawn. I don't like keeping only two males together. It often leads to bullying.
Being that Betta persephone is critically endangered in the wild, I think they should be kept in a species only aquarium, where the focus is on breeding. Particularly if they are wild-caught fish.
A 4 gallon tank is fine for one pair, but fairly close quarters for two pairs.