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Fish/Angels ganging up on pleco


QUESTION: I have a 45 gallon tank with 4 small very smart and friendly angel fish. On Sunday I added a small pleco to the bunch.  The angels have been relentlessly nipping the poor pleco, so bad that he can't come out from under his hiding spots any more.  Any advice on how to reduce this behavior? Would adding more fish (was thinking a school of tetras) take the focus off the pleco? Any other suggestions for them to act out their predatory nature other than on the pleco?   If nothing helps I'm going to have to return him so he isn't too stressed in the tank.

 I don't think adding more fish will help.  I suspect that if you add a bunch of tetras, you will end up with a bunch of dead tetras.  The one thing that might help is adding a bunch more hiding places for the pleco.  When a fish knows it has lots of places to hide (should the need arise) it is much more likely to spend time out in the open.  That said, plecos generally hide most of the time; that's what they do.  They often come out at night.

-- Ron C.
  Cichlid Research Home Page <>

---------- FOLLOW-UP ----------

QUESTION: Thank you for the advice for more hiding spots ill get something this weekend.  What species would your recommend if I were to add a few more fish?  As I stated I have a 45 gallon which leaves a lot more room.

  You might try one of the medium sized South American cichlids like Severums.  I have a tank with Severums and angels (about 50 gallons) and it seems to be working so far.

-- Ron C.
  Cichlid Research Home Page <>

---------- FOLLOW-UP ----------

QUESTION: Don't other species of cichlids need special water parameters?  The fish guy at my local store said u need to add crushed coral for substrate to do a cichlid tank other than angels, which I did not do I have gravel.

Hi Kat,
 I think you need a new "fish guy" :)  Cichlids from East Africa need crushed coral or some equivalent because they come from hard, alkaline water. Cichlids from the Amazon (like Angels and severums) come from soft, acidic water and absolutely do not want or need crushed coral, in fact, it would be terrible for them.  There are cichlids from all over Central and South America, as well as Africa and a small part of Asia and their native habitats (and preferences) differ.  In a nutshell, East Africans like hard water, Central Americans are good in neutral water, while South American and West Africans do best in soft, acidic water (but this is only a very gross generalization). ]

 Also, you would do best not to put fish from different regions in the same tank.

-- Ron Coleman
  Cichlid Research Home Page <>


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Ron Coleman


I am an expert on cichlid fishes, particularly New World cichlids. My broader expertise includes the behavior, ecology and reproduction of fishes in general. (I am NOT an expert on Goldfish). Please do not use abbreviations, such as "my GT has a swollen eye" because I don't know what a "GT" is. The more clearly you can explain your question, the better chance I have of understanding what it is that you seek. I keep fishes both as a scientist and as a hobbyist and I currently maintain about 140 aquariums.


I am an Associate Professor at the California State University, Sacramento in the Department of Biological Sciences, and I run a website, called the Cichlid Research Home Page . I also write for many popular aquarist magazines, and I was editor of Cichlid News magazine for several years. I am a scientist and I spend my time teaching fish biology, ecology, behavior and evolution and doing research on the reproductive biology of fishes, particularly cichlids. I do research in the laboratory and in Costa Rica, Nicaragua and Mexico. My main interest is understanding the evolution of parental care in fishes. I am interested in encouraging greater public awareness, understanding and participation in science.

Cichlid News, Tropical Fish Hobbyist, Freshwater and Marine Aquarium, Science, Behavioural Ecology and Sociobiology, Copeia, Canadian Journal of Zoology, Trends in Ecology and Evolution, AUK, Environmental Biology of Fishes

PhD (Toronto, 1993) MSc (Simon Fraser, 1986) BSc (British Columbia, 1983)

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