With a small group, the chaser's attention is focused on the one apparently, and it may be a female but yes it is likely to tire the one getting chased out. Stressing it out to the point of becoming ill.
It is best to get 1 male and 2 or 3 females, that way the chasing will usually be divided up more and at least some time to rest a little between attention chasing spurts.
A male will have a pointed fin next to the anal vent.
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New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?

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