Pond Boss Forums STOCKING A NEW POND Types of fish to choose koi/goldfish debate

Rowly - Hopefully you know that koi are carp (european carp) with color. These fish have been bred with with abundance of colored genes. But many of the offspring are drab colored similar to wild carp.

The koi have paired mouth barbles just like carp that they use for tasting food items while their snout is rooting in the sediments. Koi and carp both feed many hours of the day by rooting in the sediments for food. Koi can be big time competetors of your sport fish. The food items are often insect larvae that sport fish would have utilized during the insect hatch. Perch during winter can "snoot" or root out burrowing mayfly larvae asa fod source if they are present. Extensive feeding activities is due to their lack of a large stomach like many other fish who can binge feed and then rest. Koi lack this benefit thus need to feed long periods to keep their gut full.

Bottom feeding and rooting roils the water. When bottom aeration or significient wind action is present this redistributes and pumps the suspended materials into the water column. Several koi per acre can make the water more murky. Lots of koi per acre can make the water muddy. Predators will eat most of all of the colorful offspring. When cover and weeds are present the occassional drab offspring will likely survive and add to the population of rooters. When water clarity decreases the sight feeders (most sport fish) lose the ability to feeed as well as when the water was clearer.

Koi will eat fish eggs from fish that are not nest spawners i.e. broadcast spawners such as walleye and suckers. Koi may eat perch eggs since they are not guarded. Perch eggs have been reported to have offensive flavor when laid that acts as a deterrent as a food item for predators.

Everything about koi is not all bad. Their rooting activity can remix and supply some oxygenated water to the sediments. Rooting activites will disrupt plant growth trying to get established on the bottom. Cloudier and murkier pond water (Muddy water) can supress plant and algae growth due to lack of light penetration; good and bad depending on situation.

I would leave them out of a "sport fish pond" if I valued the fish and habitat. At most introduce only one or two or maybe a few that are same sex. Expert koi keepers can sex the fish esp at spawning time.