Pond Boss Forums INTRO Questions & Observations Koi?

So I'm out fishing today, and movement in the water to my left catches my eye. I look, and to my amazement, I see this HUGE koi just cruising along a foot below the surface. I know it had to be a koi because it was pure white with black spots across its back. A conservative estimate is 19" and 4 lbs. I'm guessing it got turned loose in the lake and it seems to have thrived. So I'm wondering, what the heck would this thing be eating and what (if any) predators would it have?

Koi are ornamental common carp developed hundreds or maybe thousands of years ago for their color. My koi book says 2,500 yrs ago and they originated in several eastern Asia seas and China. Records of them are from 400-500BC! Although highly colored versions appeared around 200 yrs ago. Koi were first introduced to Japan by invading Chinese. Koi keeping is a big time hobby now.

They feed like common carp. They are omnivorous which means they eat a variety of living and dead plants and animals. Most of their diet and protein source is from benthic invertebrates. They root into the sediment up to their eyes digging, sucking and straining out food materials.

Their barbels or "wiskers" (they have four two on each corner of the mouth) contain lots of very sensitive taste buds. Thus they can taste the food before gets into their mouth. Lips and fleshy mouth also contain many taste buds. Nostrils (four in all) with smelling cells also allow them to smell food odors in the water even from distant objects. Sense of smell is more important to them than eyesight for finding food.

Some of their diet is algae or soft plant material, but it amounts to only about 10%-25% other their diet. If one gets any plant/algae reduction from koi it is due to primarily their roto-tilling or rooting of the sediments. They are basically aquatic pigs or hogs. This disrupts plant life and roils the water thus causing a suppressive effect on bottom plant life. Digging action also uproots shallow rooted plants. The more of them you have the murkier your water becomes. This cloudy water is not a plankton bloom, it is suspended mud/clay/ organic particulates in the water.

PS. He was crusing just below the surface in the layer of warmest water; sort of like sunbathing. Grass carp/amur often exhibit the same behavior.
About the only predators a 19" koi has are you and an alligator.
They are fertile and will easily breed with wild carp since they are the same species.

Wow, great response as always, Bill!
I THINK there may be a couple grass carp left from when the lake was stocked, but those are sterile and won't breed with Mr Koi-zilla, correct? Also, if I want to get this ugly thing out of there, short of jumping in the water after it next time I spot him, what would be the best approach?

Grass carp/ white amur cannot theoretically breed with common carp. They are not only different species but also different genera. Genetically incompatable. In my opinion the best way to get it out would be to bait an area (same time every day - maybe early evening)with dough balls for several days then fish w/ a dough ball in the baited area. Some expert carp fishermen use softened corn as bait. Bait the area where you saw the fish. If possible do not use any weight on our line except hook (small treble) and dough ball & maybe a slim bobber. If using corn a little differnt terminal tackle is needed. Underline it out into the baited area 3' to 6' ft deep. Sit and wait; something should happen within 1/2 hr. One koi in a pond will not do irreputable damage.

I'd almost look at seeing the Koi in the pond as a bonus. As Bill says unless you are over-run with them a single Koi is pretty harmless and nice to look at to boot.

Well I've SEEN one, but that doesn't mean there aren't more out there, which is what I'm afraid of. I'm trying to raise bass and bluegill not create a 10 acre koi pond!

Well the one good thing is they are relatively easy to catch using the method Bill mentioned above. But you know there is a big market for ornamental Koi.

Koi are also sort of gregarious fish; usu hang out together or small groups, several together. You probably have only one since you only saw one. I've even seen common carp hanging with koi.

just got back in town. I have see these on about one out of every 10 subdivision lakes I manage. A couple will do little damage and kinda cool to see when bass fishing. TopH20 if you catch him I will come get him. I can sell a koi that size for some serious coin.