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Aggressive emperor tetras


25 Aug 2017
I have 260l tank with 5x emperor tetras, 10x neon tetras, 3x angel fish, 1x ram, 1x otto and 8x small bronze corys. All but corys have been in the tank for years and their school numbers have gone down over time.

Problem is very aggressive possibly male emperor that bullies pretty much anyone else par angels. This has increased since adding corys meaning that angels hang out at left of the tank, one emperor keeps his rein of terror at the middle and everyone else tends to take cover at the right of the tank under anubias.

I’m not entirely sure what to do to stop this. Add more emperors to keep the bully occupied? Do something to change the set up with plants? Get rid of the emperors and get more chilled fish?


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I was afraid that would be the answer but thanks anyway. I do remember them having wars even when there was 10 of them tho.

I’m very much in process of reorganising the tank after Cyanobacteria hell and getting all fed up with the whole thing. Cyanos have finally disappeared and I’m fairly nervous getting any higher maintenance plants or to do any major reshape as it all goes horribly wrong when I start mucking about with it. The crypts on left have been there for over a year without growing or dying even with root tabs so I’m not entirely sure what would grow there.
I have kept emperor tetras for nearly 40 years and haven't really seen any major aggression with other species. I have a breeding tank with perhaps 100 of various ages and other than odd nipped fins they are active but not belligerent . In my 350l house tank i just have 4 adults and the dominant male constantly chases the females and anything else but there's no aggression towards the (mainly) killifish and corys and even the adult cherry shrimp survive. even though he's the biggest fish in the tank I think an Aphyosemion caudofaciatum male is dominant. Having said that, my tank is overgrown and there is lots of cover for everyone :D
I had a double check on my fish and think that they actually are rainbow emperors Nematobrycon lacortei rather than N.palmeri that I bought them as which make obtaining more a bit more tricky. Apparently they may be more aggressive or perhaps I have particularly megalomaniac individual. In the meantime I’ve reorganised tank fair bit in hope that it messes up territory sufficiently and will add more plants when I work out what do I want/ can keep alive