As the temperatures drop and daylight hours shorten, pond owners may start to notice changes in their aquatic environments.
From slowing metabolisms to shifting water chemistry, winter creates unique conditions for backyard ponds. Whether you’re in chilly Tasmania, frosty inland New South Wales, or more temperate areas like Brisbane or Perth, knowing how to care for your pond during the cooler months is crucial for the wellbeing of your fish and the long-term health of the ecosystem.
1. Understanding Seasonal Changes in Your Pond
As air temperatures drop, your pond water cools down too, especially in regions where winter nights can dip into the single digits. When water temperatures fall below 10°C, the metabolism of fish like koi, goldfish, and native species slows significantly. They eat less, swim less, and become more sluggish. This change is natural, but it means your approach to feeding and pond maintenance needs to shift accordingly.
Additionally, lower temperatures can impact beneficial bacteria that help manage water quality. These bacteria also slowdown in winter, which can lead to an accumulation of waste if not managed properly.
2. Feeding Fish Less—or Not at All
One of the most important rules of winter pond care is to reduce feeding as temperatures drop. Fish do not need as much food in cold water because their digestion slows. Feeding them too much can lead to uneaten food rotting in the pond, causing dangerous spikes in ammonia and other waste products.
Use a pond thermometer to keep track of water temperature accurately, and never feed fish if they’re not actively swimming or seeking food at the surface.
3. Managing Water Quality and Filtration
While your fish are less active in winter, your pond still needs good filtration and aeration to prevent a buildup of toxins. Don’t shut down your pond filter unless necessary.
Here’s what to do:
• Clean your filter to remove accumulated sludge before winter sets in.
• If your system includes a UV clarifier, you can consider switching it off if algae growth is under control, but keep water circulating.
• If you use a pump or waterfall, keep it running to ensure proper oxygen levels and water movement.
Oxygen levels can drop in winter, especially at night, so aeration is still important even if fish aren’t as active.
4. Remove Debris and Clean Up
In autumn and early winter, make time to remove fallen leaves, twigs, and organic matter from the pond. As this material breaks down, it releases harmful gases and can impact water quality.
• Use a net or pond vacuum to clean up debris.
• Consider placing a pond net over the surface during peak leaf fall in colder regions.
• Cut back dead or dying pond plants, particularly marginal and floating plants.
This proactive cleanup helps reduce the nutrient load in the pond and makes it easier for the biological filtration system to do its job.
5. Watch Water Levels and Top-Ups
Even in winter, ponds can lose water through evaporation, especially on sunny days in drier climates. Keep an eye on water levels and top up as needed, using dechlorinated water or a water conditioner if using tap water.
Avoid large water changes unless absolutely necessary during winter. Drastic changes in water temperature can stress fish that are already in a vulnerable state due to slowed metabolism.
6. Protect Fish from Predators and Temperature Swings
During winter, fish may spend more time resting at the bottom of the pond, where the water is slightly warmer. This makes them more vulnerable to predators such as birds or cats, especially in shallower ponds.
To protect your fish:
• Add pond shelters, lily pads, or fish caves.
• Use a pond net or floating plant cover to offer some protection.
• Avoid tapping the ice or making sudden loud noises near the pond, which can stress fish.
7. Plan Ahead for Spring
Winter is also a great time to plan for spring maintenance. Consider:
• Inspecting pond liners and structures for damage.
• Scheduling a filter service or pond clean for early spring.
• Researching new plants or fish additions once the pond warms up again.
By staying on top of winter care, you’ll be ahead of the game when the temperatures start to rise.
Caring for your pond and fish in winter doesn’t have to be complicated, but it does require awareness and adjustment. By modifying your feeding routine, maintaining equipment, and monitoring water quality, you can ensure that your pond remains healthy, and your fish come through winter strong and ready for the warmer months.
Whether you’re managing a small garden pond with a few goldfish or a large pond with elaborate filtration, winter is a time for gentle observation, routine checks, and preventative care. Your fish will thank you come spring with vibrant health and active behaviour—proof that good pond care never goes out of season. Speak to the Pet Experts at your local Just For Pets independent pet store for more information.
