From my experience a group of 5-6 is needed. Then for some reason they just calm down and leave tank mates alone. I kept a group in a 125 until they were about 8-9 inchs with catfish, SDs, severum without a problem until finally lost everything during a power trip.
Only thing is they can't stand the sight of other similar species like head standers or flagtails.
Thank you so much for this info I was hoping for and more. Great to know.
And they eat normal feeds, right? I am trying to respond to earlier statements that they are parasitic fin, barbel, and scale eaters, which was stated in general. I can be corrected but at present I don't think so. They eat pellets and cut fish in my hands. They are not parasitic by nature at all. It's just something they may do (occasionally, maybe rare maybe often but not all the time!) to cope with the stress of not being in a shoal / school.
No wonder animal rights groups are closing in on this hobby. I can't believe in this day and age that people suggest mutilating fish to curb a minor problem.
Please just rehome, don't go Dr frankenstein on your fish.
Agree.
But thinking aloud...
People dye, mutilate, disfigure, etc. their pet fish to please their unorthodox tastes. I mean if they buy such fish, they do it to them. People do same things to dogs and cats. They are called "designer" pets. I am not defending earlier comments but saying it's just one suggestion in a sea of pet suffering. Pugs ca't breath. Hairless cats freeze. Geese are force fed corn to make their livers sick and enlarged. Long-fin, triple tail fish, balloon fish, etc. can't swim. Short body fish can't house their internal organs and their backbone is folded.
We as a civilization do unspeakable things to animals of all kinds to satisfy our twisted palates and eyes.
I wish we ourselves, personally, became wiser and neither participate or support directly or indirectly, nor aid or abet in any activity, commercial or not, that does this.