Why Do Koi Jump?

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Jumping Koi Fish

Koi fish are interesting creatures to say the least.

For anyone who’s had fish, any fish really, for any length of time, you kind of get in tune with their habits and personalities, and yes, they do differ from fish to fish.

And one trait that some of them may have is that they like to jump.

Now before you “jump” to any conclusions, you can rest assured that sometimes Koi just jump for the fun of it. Makes sense if you think about it. From Koi to carp to whales and dolphins flying freely, tell me you don’t think it would be fun to go airborne if your world was mostly made of water.

Some individual Koi really like to leap, and that’s fine as long as they’re safe. The real problem with jumping Koi, isn’t so much that there’s anything wrong in the pond, but if they don’t happen to land back in the water, you’ve got a problem. It might end up being their last care-free act.

And this goes for fish being kept in holding tanks during the winter too. More than one Koi lover has found a flying fish flopping on the garage floor. For temporary housing, putting some netting or covering over the tank is a pretty easy fix. So you might keep this in mind during your off-season routine.

Don’t Assume All Is Well

I think it’s fairly reasonable to assume that if a pond owner see’s a fish jumping, or finds one on the ground, most of us would get a little worried. As I mentioned before, just because a fish jumps doesn’t mean something is wrong, but it really could be looked at as a signal of some kind of problem, and particularly when you see several fish jumping a lot, then it’s definitely time to do some investigation.

The first thing to do is to test the water. Two simple tools will make this pretty easy. Use 5 and 1 test strips to check the pH, alkalinity, water hardness, nitrites, and nitrates. The most important of these is pH (and nitrites second). Koi in particular don’t like low pH (or really high pH for that matter but they may tolerate it a bit better), on the low end, for example it would be around 6.5 or less. Check your source water too if you’re having to add water often due to hot weather, etc.

The second thing you’ll want to look at is if any ammonia can be detected in the water. Ammonia test strips are useful here and really no amount or level should be found. If you do detect some ammonia, do some partial water changes to bring it down and look at adding some good bacteria to the water to help neutralize it. The same really could be said for nitrites which are also problematic in ponds with fish. Routine use of a good bacteria should help with this.

Fish may jump due to any kind of discomfort, meaning basically that they don’t want to remain in the water for some reason. Issues could include low oxygen in the water (and we fix this with adequate aeration), skin irritations or parasites, or during breeding periods, females may jump just to avoid the affections of male suitors.

And one final thing to consider is chlorine. I think many new pond owners just don’t think of this but chlorine or chloramines, two very popular disinfecting additives that are used in most city water sources, simply are not good for fish and it will kill them if concentrates are high enough. It’s really not that good for your plants either. So an easy remedy for this is to use dechlorinating tablets or a dechlorinating filter that attaches to your garden hose.

So remember, a flying fish, every now and then, might just be having some fun, and that’s a sign of a happy fish. I’d still suggest you follow through with the simple checks I mentioned above just to be sure all is well in your pond.

Koi photo credit tofucamera

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2 thoughts on “Why Do Koi Jump?”

  1. thanks Mark, your news letters are a great deal of info. i only have a 40 gal pond with too many gold fish, that would be clear for just a few days than turn green. with the great info from news letter and doing what is sugested. i have the beutifull gold fish pond that you see in pitchers . with your news letter and your knowlage i have done this in less than 6 mo. when this could have been years of not having such a show peace in our yard! hpoe every one has a blessed holiday and a safe one

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