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Fish/flowerhorn fish


i am having some issues with my 13 inch long flowerhorn, i have had it more than 5 years now, since then i have treated my fish many times for hole in head parasite, mostly with metronidazole, it worked....lately i see that it is developing it again and also has a swelled up belly, not eating more than 2 pellets a day, and in the usual corner....
i think i am not completing the medication properly and hence the problem is recurring, i would like to ask for your guidance in this much dosage, as of now following 5mg/pl of flagyl, can i use metronidazole I.V fluid instead ?, also how long medication should continue...thanks for your help to give some advice.

Hi Samir,
  It seems that while you are treating the symptoms, you may not be treating the problem.  Hole in the head most often results from poor water quality. Treating it with medicines may get rid of it for a time, but if the poor water quality continues, then it will come back.  How often are you changing the water in the fish tank?  Also, be sure that you are not overfeeding and that there is no excess food in the tank -- that is the usual cause of hole in the head.

-- 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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