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Fish/Gold Molly Fish Black Eyes?



I've had my tank of 4 mollies and 2 platies for about 6 months now, however every maybe 6 weeks a single molly fish dies (yet never the platies), and it seems to be from unknown circumstances. I clean my tank regularly, feed them according to the directions the manager at the pet store gave me, and make sure I change the water regularly. what may be causing the deaths, if it happens occasionally and not at once? (I'm left with 1 molly and 2 platies now)

Also, I found my earlier healthy golden molly to be floating around the tank vertically, fins extended but not breathing, and it's eyes had gone black. What could have caused this? I want to try and ensure my tank is fit for them, as I was sure it was.

Hope you can help,


Hi Danielle,
  Given that it sounds like you are doing a good job with the water conditions, the most likely culprit is that one of the remaining fish is attacking the others.  Are there any other potential signs of violence, e.g., torn fins or perhaps a missing scale or two?

-- Ron C.
   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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