As winter approaches, pond owners often wonder how to best care for their fish during the colder months. For outdoor ponds, fish like koi and goldfish naturally enter a state of dormancy, conserving energy as the water temperatures drop. But what if you decide to bring your fish indoors for the winter? Is this a good idea, and how can you ensure their well-being in an indoor tank?
Why Move Fish Indoors?
Outdoor ponds can freeze during the winter, especially in regions with harsh winters. While fish can survive in partially frozen ponds as long as they have access to oxygen and the water doesn’t freeze solid, some pond owners prefer to bring their fish indoors to avoid the risks associated with freezing temperatures. If you want to keep your fish in your pond throughout the winter, read our blog, How To Keep Your Goldfish And Koi Safe Through Canadian Winters.
Moving your fish indoors provides them with a stable, controlled environment free from the dangers of ice formation, fluctuating temperatures, and potential predators. You may place them in a cool environment, allowing them to become dormant, or move them entirely inside the home. This allows you to keep them active and healthy without causing them to enter a dormant state. We want to explain the considerations for both.
What Happens When Fish Go Dormant?
In their natural environment, pond fish like koi and goldfish enter a dormancy known as torpor when the water temperature falls below 50°F (10°C). In this state, their metabolism slows dramatically, they stop eating, and they move very little, often settling near the bottom of the pond where the water is more stable and warmer. In this state, they do not need to be fed. Adequate aeration, filtration and water changes are recommended.
While dormancy is a natural survival mechanism for fish, it comes with certain risks. The fish could be in danger if the pond freezes completely or the oxygen levels drop too low. Moving your fish fully indoors eliminates these concerns, but there are a few things to remember.
Creating a Winter-Ready Indoor Environment
If you decide to move your fish into an indoor tank for the winter, here’s how to create a comfortable environment:
- Maintain Stable Water Temperatures
Indoors, your fish won’t enter dormancy since the water will remain warmer than in an outdoor pond. For koi and goldfish, keeping the tank water between 65-75°F (18-24°C) is essential. You can use a reliable aquarium heater to maintain a consistent temperature. Sudden fluctuations can stress your fish, so avoid any rapid changes. - Ensure Adequate Space
Fish that live in large outdoor ponds are used to having plenty of room to swim. If you’re bringing them inside, be sure the tank is large enough to accommodate their size and swimming habits. Koi, in particular, can grow quite large, so choose a tank with ample space. Overcrowding can lead to stress and poor water quality. - Invest in Good Filtration and Aeration
With the fish remaining active, their metabolism will stay higher than in the dormant state, meaning they will continue producing waste. A robust filtration system is essential to maintain water quality and prevent harmful ammonia buildup and other toxins. You’ll also want to ensure the tank is well-aerated, as fish require plenty of oxygen, especially in a more confined indoor space. - Water Quality Maintenance
Use CWP Pond Cleaner, CWP Phosphate Binder, and CWP Muck Remover regularly to manage nutrients and reduce waste buildup. These treatments help keep the water clear and healthy, minimizing stress on the fish. - Keep a Consistent Light Cycle
Fish are sensitive to environmental changes, and light plays a vital role in regulating their natural rhythms. To help your fish adjust to their indoor surroundings, mimic the natural day and night cycle by providing a consistent light source during the day and allowing for darkness at night. This will help keep their stress levels down. - Feeding Your Fish in an Indoor Tank
Unlike during dormancy, when fish stop eating entirely, indoor fish will continue to feed as usual. However, be careful not to overfeed them, as excess food can contribute to poor water quality. Feed your fish sparingly, ensuring they consume all the food within a few minutes.
Preparing Your Fish for the Move
Before moving your fish indoors, it’s important to acclimate them to the environmental change. If possible, gradually raise the temperature in the outdoor pond or introduce them to the indoor tank water over a period of time. This will help minimize shock from sudden temperature differences.
When transferring the fish, use care to prevent injury and stress. Transport them in a large container filled with their original pond water to help maintain their familiar environment as they transition to the new tank.
The Benefits of Bringing Fish Indoors
Moving your pond fish indoors during the winter can be an excellent option for those living in colder climates or for pond owners who want to avoid the risks associated with frozen water. With the proper setup, your fish can remain active and healthy throughout the winter months, and you won’t need to worry about their well-being in a frozen pond.
By keeping the water temperature stable, providing enough space, ensuring good filtration, and maintaining a proper light cycle, you can create a comfortable and healthy indoor environment for your fish.
If you have any questions or concerns about caring for your koi and goldfish in winter, don’t hesitate to contact our water experts!
