IMO a pair as well. I've kept many pairs of these, usually have a pair in almost every setup size permitting. Maled hardly ever if at all exhibit the red spots on the stomach, another thing is over the the forthcoming coupled of weeks the male will grow a lot larger than the female.
When very young they tend to spawn a lot so it shouldn't be long before you know for sure. They're awful parents though when kept in a single pair probably because the majority of these fish are artificially spawned. The "pairs" also tend to fall out a lot. They don't really pair up as such and would swap partners willy nilly given half the chance but as they have no choice of partners they will fall out but get together just to do what nature intended. Either fish will tend to eat the eggs when they get bored of each other. Probably why they get artificially raised so much which then has the down side of passing on the not really caring about their offspring gene.
Very popular in lfs so breeders don't leave it to chance. I've kept these fish and tried to breed them for decades and have yet to raise any spawn, for that matter I don't think I've seen anyone else either. Never tried removing the eggs though, maybe one day. They are also very susceptible to hexamita. Once treated for worms though they are pretty bullet proof. They are also quite prone to just popping their clogs with no apparent reason, just starts off with striping up and heavy breathing when all other fish are well.
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