Adding more Candy Canes will probably not solve the problem since you will just have more fish that can attack the emperors. You need to change one of the species and add others that match their personalities. Not all Tetras are safe to mix together. Generally, the fish with the same body shapes get along. You have an elongated one ( emperors) and a circular one ( candy canes.) Circular species tend to be more aggressive and fin nippy but that's not all species of circular ones. You really have to do your research before mixing Tetras. Keep in mind that your Candy canes are related to piranhas.
In fact , all Tetras are related to Piranhas ( some just more distantly than others.
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I've been observing the tank, and the candy canes don't seem to be the problem. They are juveniles and the emperors are grown and larger than the cc tetras- at this point, anyway, I don't see the cc tetras bothering the emperors at all. I did neglect to say that 6 of the emperors are from my elderly mother's tank, rehomed recently back to my tanks, though still all from the same original pair that birthed them. And all the tail injuries have happened to males only. AND I've been noting that they're more raucous than normal since the two batches of them came together.
I've kept emperors on and off for years, and they're more aggressive than the internet leads you to believe, though with enough space, in my experience, the males mostly keep it confined to chasing and arguing with other males. Never before have I seen them with as serious of the injuries I've seen in this tank (I do know if you crowd them a little, the aggression can go up).
In short, they're the only fish I see sniping at each other in the tank, so my current theory is that the new group and the old group of males are fighting for dominance. What's still a question mark for me is the level of injury that two of them have sustained on their tails. Never seen that before.
Most any schooling fish feels better in a larger school, and six is kind of a minimal school, so it feels entirely logical to think that adding more of the candy canes might make them feel more secure. But either way, I've just seen no nipping behavior from these juveniles as of yet.
If I see any new injuries (I've moved two of the emperors with the most obviously injured tails into quarantine in a 10 gallon and added salt with an eye to their recovery), I'll probably post a video of the tank. But so far, since removing the two, it seems a bit more like business as usual between the remaining males. And no new injuries.
I haven't read any article or anybody's experience talking about serious interactions between emperors and cc's (though I haven't scoured the aquarium groups for that). In general research on the 'net, they're both called "peaceful" though it's mentioned that the cc's are nippers. As I've said, I only have prior experience with emperors, and they can bully on a dime if you're not careful with them and smaller tetras.
Thanks for the help, btw! I've read a lot as a lurker on the aquarium groups, but never really participated before.
