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Do you have any water quality tips for bringing koi inside for the winter?
Ask Our Pond Experts
Ask Our Pond Experts

Do you have any water quality tips for bringing koi inside for the winter?

Asked By: Shiela of Norton, VA

A: Koi are hardy, cold-water fish well-equipped to handle frigid winters as long as they have a deep pond to escape the chill. However, if you have a shallow or above-ground koi pond, you should bring your fish indoors when the weather dips below freezing. To make their stay pleasant, take the following steps to maintain water quality.

Reduce Stress and Shock

The primary risk when moving koi indoors for winter is shock due to the stark change in water conditions. Add old pond water mixed with tap water and conditioner to your indoor koi fish tank to minimize stress and reduce this risk. The Pond Guy Stress Reducer Plus water conditioner removes harmful heavy metals, chlorine, and chloramines and fortifies your fish's protective slime coat.

Install Aeration and Filtration

Your indoor holding tank will likely be much smaller than the outdoor pond koi are used to. The cramped conditions can negatively impact water quality without an aquarium filter and air pump for your fish tank.

PondAir Aeration Kits infuse water with fresh oxygen but don’t provide filtration benefits. If you don’t have an aquarium filter, an in-pond filtration system sized for your holding tank provides mechanical and biological filtration with enough aeration to maintain water quality. We recommend the Pondmaster 1250 Filter Kit for tanks up to 600 gallons.

Boost Beneficial Bacteria

Add beneficial bacteria to winter aquariums to digest waste and reduce phosphate and nitrate levels in the fish tank. The Pond Guy LiquidClear keeps the water clean and reduces the load on mechanical filtration systems. These tiny microbes activate as soon as they hit the water, multiplying rapidly and digesting dead organics.

No Chemicals Necessary

Unless your holding tank receives a lot of sunlight, you probably won't need chemical treatments like algaecides or water clarifiers. Keeping up with beneficial bacteria, water conditioner, filtration, and aeration will result in crystal-clear water and happy koi fish all winter.

More Tips for Overwintering Koi Fish

Keeping koi indoors is easy once you understand what your fish need. Our friendly, fish-loving pond experts are here to answer all your koi care questions. Just give us a call at 866-766-3435 today!

Check out these additional guides for overwintering koi fish to learn more:

Overwintering Koi Fish Indoors
Overwintering Koi in Your Pond
Are My Fish Winter Hardy?
Protecting Fish in the Winter