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Emperor Tetra – Fin Rips? Likely Culprits?

Home Forums Fresh and Brackish Water Fishes Emperor Tetra – Fin Rips? Likely Culprits?

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    Hey guys.

    Tonight whilst looking at my tank, I realised some of my Emperor Tetras have damaged fins.

    My stock list is:

    6 x Congo Tetra
    5 x Emperor
    6 x Glow light
    9 x Neon
    2 x Plec
    2 x Guppy

    I would imagine that the congos are most likely to be the culprits for this? The one guppy seems scared to death of them so I will be transferring both of them to a different tank tomorrow.

    I’ve had the congos and most of the emperors about a month now.

    Also the one male emperor has a slight pale patch near his head on his side which can be seen in the photo below. Do you think this is anything to worry about?

    Here are some photos. Do you think my stocking of congos could be making the other fish stressed? Are their fins likely to grow back?




    Byron Hosking

    I cannot see the white patch issue from these photos as the lighting is bright and the fish are thus not clearly defined.  I’ll just comment on your fin nipping possibilities.

    This is very unlikely to be the Congo Tetra.  It is more likely the Emperor themselves, but the glowlights are not entirely ruled out.  Tetra are shoaling fish by nature, which means they have an inherent need to be kept in groups.  A scientific study a year or so back showed that below six caused shoaling fish to feel insecure and aggression was often heightened, even within otherwise peaceful species.  Tank size (and the environment) also plays into this, and you haven’t mentioned the tank size here.  With six glowlights, and given the traits of this species, I would suspect the Emperors first if nipping is involved.  I would certainly add more of them, up to 7-9 if tank space permits.

    One cannot rule out a bacterial issue, which might involve the white patch and fin damage, but without clearer photos it may be impossible to say.  And I am not the one to help with disease, but other members undoubtedly can.




    Hey Byron!

    Thanks for your reply. I had a 6th emperor but unfortunately she contracted a disease last week that all but killed her and I had to euthanase her :( Here is a photo of what she had:



    I am keeping a close eye on the others to make sure I cant see it on them. 

    The slightly white spot on the male emperor can be seen just behind his gills in the first photo of the last post. (the rightmost fish). 

    The tank is a 200L Fluval Roma 200. The fin issue is definitely nips rather than rot. 



    Byron Hosking

    On the reddish growth/ulcer in the latest photo (the dead fish), I had this only a couple weeks ago on a Black Phantom.  When I see this, I try to net the fish out and euthanize it.  The fish slowly weakens to the point it is easy to net.  I’ve no idea what this actually is, but I have read that euthanizing the fish is likely best.  I have never known it to spread after doing this, and the affected fish never recovers.

    To the whitish spots, which I seem to see on both fish, I am wondering if it is just normal colouration?  It seems to be highlighted by the light.  I would keep an eye on this.  Without knowing exactly what a disease is, using any medication can be dangerous.  I have killed fish without curing the disease in the past, which is why I am now so cautious and prefer euthanizing a single fish.

    If there is fin nipping, I would suspect the Emperors.  I gave away my group of Emperors because they terrorized the other fish.  A few weeks later, fry appeared in the tank, so obviously they had spawned prior to my removing them.  The fry grew, twelve in all, and I watched to see how they would behave.  Once or twice they sort of looked a bit sneaky, but over a period of several months they behaved themselves.  It may have been that growing up in this tank with other fish from the start was the difference.




    Emperor Tets are very nippy wth one another, but I’ve never (I’ve been keeping and breeding them continuously for over 20yrs) seen damage to that extent, so I’m going to disagree and suggest that the finnage of the Emperors may be triggering a response from the Congos (which really can knock lumps of each other, especially breeding males).

    I can’t see a whitish patch either, but many Emperor Tets are wild imports and so may come in with encysted fluke larvae and the like which might result in a pale patch under the skin, or it could be a healing injury. If the fish is active and feeding I wouldn’t worry.



    The red lesions look like Piscine Tuberculosis (always fatal once it breaks out). Many aquarium fish seem to carry this infection but do not show symptoms unless they are stressed. Humans can contract it as well . If you have cuts/abrasions on your hands and put them in an aquarium containing infected fish. It’s easily cured apparently. Your other Emperors look fine apart from the nipped fins.



    I agree that the red lesions could be due to fish TB (mycobacteriosis). However, I don’t know how susceptible this species of fish is to mycobacteria. A definitive diagnosis would usually require histology or a DNA test.


    Humans can contract it as well. If you have cuts/abrasions on your hands and put them in an aquarium containing infected fish. It’s easily cured apparently.

    Unfortunately, it is not easily cured in humans. I have known several people who have caught this.

    Here is a link to an on-line disease book (specifically written for zebrafish, but also generally applicable to other fish) written by fish vets who actually do research on this disease.



    Gloves and washing hands with alcohol and considered possible preventatives.

    Also of interest about this disease: it is NOT an obligate pathogen. This means that it can make a living hanging out in a tank with out requiring fish to infect and then infect them later.

    Among the many possible sources of fish, few sources produce that are not contaminated with this pathogen (this would be fish from a handful of labs and very few fish farms (the 5-D fish farm in Florida is one). Fish going through pet or fish stores have probably be exposed to the pathogen left be previous fish going through the store.



    I was also thinking myco but didn’t want to be the one to say it. Adrian Tappan has written an excellent pamphlet on the subject and has most generously offered it freely online.




    Yes, looks like Myco is a strong possibility. ASAIK, tetras are quite susceptible to it. Some of the fin problems may be caused by myco as well (secondary infections develop in fish that has been weakened by Myco).

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