Question posted by Dave: Will siamese fighters get along with any other species in the same tank?
I can’t give you an experts advice as to what fish siamese fighters get along with, but I have seen them together with other fish many times. As long as the fish are equal in size there shouldn’t be any problems. Female fighters can be kept in the same tank, given enough room and some time to get used to each other. Male fighters have to be kept seperate from other male or female fighters.
A better description (from VickiPS, Ipswish, QLD)
Individual bettas vary in temperament, and a very aggressive male may not tolerate tank mates, but generally a single male betta will get along in a community tank with other non-aggressive species that aren’t (a) nippy (and likely to be tempted to nibble on a betta’s fins) (b) either too slow, too active or too timid, and (c) fancy-finned (and therefore likely to provoke the same reaction as another male betta). Other labyrinth fish species are best avoided, too.
It limits choices a bit, but corydoras are usually compatible, as are many of the non-aggressive tetra species (eg. neons, diamond tetras). Harlequin rasboras and pacific blue-eyes are other possibilities. I’ve had a male betta sharing a tank with 3 albino corys and a bunch of neon tetras for nearly a year, with few problems.