My family got 3 pond fish which were koi. I realized one fish was getting bigger/swollen looking.

After a few months he was getting really swollen or big and during the month he stopped eating.

I was so worried because he was the kind of fish that would come to you and let you pet it.

Today he died. I'm not sure what caused it. Recently a frog joined our pond and I'm not sure if he caused it. I would really want to know if the frog was the reason and how I could have prevented it.

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  • 2
    What size pond is this and can you explain your feeding schedule and the filtration and maintenance that you do for it? The frog is definitely not the problem. It's common for both frogs and turtles to end up in outdoor ponds and they rarely cause any problems.
    – Jestep
    Commented Aug 18, 2016 at 20:18
  • What do you mean by "I was so worried that he was the kind of fish that would come to you and let you pet it. "? Are you RJHay and if not do you have his permission to use her_his photo? If yes, please leave a note. Commented Jan 15, 2017 at 23:37

1 Answer 1


is your fish the one in the picture, I presume so? If so, how long was it taken before the fish died? It is swollen, as a female would be with eggs. Were the scales protruding a bit, like a pine cone when it opens? Your photo is not clear enough for me to really judge. If they were it could be dropsy, or the pine cone disease. It is caused by a bacteria eaten by a fish. It could be a dead fish or frog that she has eaten, and the bacteria can linger for a long time, until the fish is stressed in some way or other. If it died of dropsy, when the scales protruded it was already too late. There is absolutely no cure for it, unless science has progressed to test the fish before it's scales are raised, before the fish shows signs of sickness. It looked a good quality kohaku. It is virtually impossible to be sure by a photo; imagine going to a doctor and him/her taking a photo to see what is wrong with us. regards gary

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