well im not sure but some one else will be able to tell you better persoaly i wouldnt like to, i only house bettas in 15L + i feel its alot safer![]()
keep in mind this isnt literally one fish in a 12.5L box. theres 25L of water, just a physical barrier stopping the fish getting at eachother. they both have the 25L of water, they just dont have the whole physical space of the tank to use.
i dont know anything about bettas, but from what i see its important not to think of this like you would "can i put a betta in a 12.5L tank?". i think theres a difference in this situation.
Its down to you really, if you feel that 2 males would be happy in a split 25 Litre then do it![]()