Caring for your pet fish in winter
As winter settles in, the needs of your pet fish may change, and it’s important to adjust their care to ensure they stay healthy and comfortable throughout the colder months. Whether you have indoor or outdoor fish, there are key steps to take to maintain their well-being during this time. Here's how to keep your pet fish safe and happy this winter.
Do fish hide in the winter?
During the winter months, garden pond fish exhibit certain behaviours that are entirely normal, as their metabolic processes slow down due to cooler temperatures. Understanding these behaviours can help ensure that your fish remain healthy and stress-free throughout the colder season.
Pond fish tend to seek shelter during the winter, either in deeper areas of the pond where the water remains slightly warmer or beneath submerged plants, rocks, or pond features. They often remain near the bottom of the pond, where temperatures are more stable. This is perfectly normal, as it helps them conserve energy and stay protected from the cold.
As temperatures drop, the metabolism of pond fish slows considerably. You’ll notice that your fish become much less active, often spending more time at the bottom of the pond or near sheltered areas where the water is slightly warmer. Fish may move slowly, and their swimming may appear sluggish. This is normal and a natural response to the colder water.
How to keep pet fish healthy in winter
As the temperatures drop, it’s important to adjust your care routine for your pet fish to ensure they stay healthy and comfortable throughout the winter months.
Monitor water quality
Water quality is essential for the health of your fish year-round, but it’s especially important during winter when colder temperatures can slow down the filtration process.
- Test water parameters: Regularly check the pH, ammonia, nitrite, and nitrate levels in your tank or pond. Cold water can reduce the activity of beneficial bacteria that break down waste, so ensure your water is still clean.
- Water changes: Perform partial water changes regularly (about 10–20% every two weeks), even in winter. This will help maintain optimal water conditions and prevent harmful toxins from accumulating. In ponds, make sure to remove debris like fallen leaves that can pollute the water.
Maintain proper water filtration
While your fish might be less active, it’s still important to keep the water clean and well-oxygenated.
- Indoor aquariums: Ensure your filter is functioning properly. Cold water can slow down the filtration process, but the filter still plays an important role in keeping the water clean and free of toxins. Clean the filter regularly, but avoid over-cleaning as this can disrupt the biological balance in the tank.
- Outdoor ponds: If you have a fish pond, ensure that the filtration system is designed to work in colder temperatures. Clean your filter to prevent it from becoming clogged with leaves or other debris. If ice forms over your pond, consider using a de-icer or aerator to keep a hole in the ice for gas exchange.
Prevent freezing
For outdoor fish, freezing is a serious concern. In ponds, ensure that the water doesn’t freeze completely by adding a floating pond heater or using a de-icer to keep an opening in the ice. This will allow the exchange of gases and prevent the water from becoming stagnant.
For indoor tanks, check for drafts or temperature fluctuations in the room that might affect the water temperature. Keep tanks away from windows, doors, or radiators to maintain a stable environment.
How to keep pet fish warm in winter
Most fish are sensitive to temperature changes, and winter can pose a challenge for those kept in tanks or outdoor ponds. For most pet fish, maintaining a stable water temperature is crucial, especially during winter.
Tropical fish
These fish thrive in warmer water, usually between 24°C and 28°C (75°F to 82°F). If you have a heater in your aquarium, make sure it’s working efficiently and adjust it to maintain a consistent temperature. Always use a reliable aquarium thermometer to check the water temperature regularly.
Coldwater fish
If you have coldwater species (e.g. goldfish), they can tolerate lower temperatures, but you should avoid letting the water freeze. In an outdoor pond, ensure the water remains above 4°C (39°F), as most pond fish go into a dormant state when the water gets too cold. Install a pond heater or de-icer to prevent the pond water from freezing over completely. These devices are designed to keep a small area of the surface from freezing, allowing for oxygen exchange and ensuring that the fish do not suffocate.
If it is already frozen don't break the ice as this can harm the fish, but carefully place a saucepan of hot water on the surface to gently melt a hole in the ice. Never tip boiling water straight onto the pond either, as this can also harm or kill any fish living there. Never try to use antifreeze or salt to thaw frozen ponds or birdbaths.
Regulate the water temperature
Keeping your pet fish warm during the winter months requires a combination of the right equipment, careful planning, and consistent monitoring. Use heaters to regulate the water temperature, place the tank in a stable, warm environment, and make sure to insulate the tank or pond properly to prevent heat loss.
For outdoor ponds, a pond heater or de-icer can ensure your fish remain comfortable and safe. By following these tips, you can help your fish thrive and stay healthy throughout the colder months.
How to keep pet fish safe in winter
Winter can sometimes stress fish due to the cold, so it’s essential to keep a close eye on their health. Look for signs of illness, such as lethargy, loss of appetite, or unusual behaviour. If you notice any of these symptoms, check the water quality and temperature to make sure they’re within safe ranges. For outdoor fish, consider protecting them from harsh weather by adding covers or netting to your pond. You can also reduce the risk of illnesses by avoiding rapid changes in water temperature, which could stress your fish.
If you suspect your fish are sick, consult an aquatic vet. They can help diagnose and treat illnesses before they become more serious.
Common winter poisons
During the winter months, pet fish are at increased risk of exposure to various environmental toxins that can harm their health. These poisons can stem from water quality issues, improper heating, or contamination from external sources. Here are some common winter toxins to watch out for and tips on how to avoid them:
- Ammonia - toxic compound that forms as fish excrete waste and uneaten food breaks down, can cause gill damage, stress, and even death in fish
- Nitrate - a result of ammonia breaking down, can impair oxygen transport in the blood, leading to suffocation
- Chlorine and chloramine - chemicals commonly used in tap water, can cause damage to gills, skin, and overall health. If exposed symptoms can include gasping, inflammation, or even death
If you suspect your fish have been poisoned, consult an aquatic vet. They can help diagnose and treat illnesses before they become more serious.
Winter brings several challenges for pet fish, but with careful attention to water quality and environmental conditions, you can protect your fish from common winter poisons.
Regularly monitor your aquarium’s or pond’s water parameters, ensure proper filtration, and be cautious with chemicals and treatments. By taking these precautions, you can help ensure your pet fish remain healthy, safe, and comfortable throughout the winter months.