During warmer weather pond fish are very active and can be seen happily swimming around but what happens when winter hits.
Pond fish are cold-blooded (Poikilothermic) so their metabolism is controlled by the water and temperature that they live in.
As winter takes hold and the water in your pond drops in temperature your fishes metabolism slows down to a crawl.
When this happens your fish will retreat to the deepest and warmest part of your pond where they will spend most of their time treading water.
However every now and then they will swim a little bit because they need a little movement to stop their joints seizing up.
As long as you have a deep area of about 18″-24″ in your pond your fish will be safe and away from the cold area at the surface of the pond.
What can I do to help my fish during winter months?
As autumn turns to winter you need to control your fishes eating habits.
Throughout the warmer months your fish are very active and need a high protein diet to keep them going, as colder weather descends fish need less food and less protein.
As winter draws nearer and the temperature starts dropping you only need to feed your fish 2-3 times a week before changing their diet to a non-protein based food such as a wheat germ when the temperature drops to 10 degrees. Use a pond thermometer to check the water temperature.
Feeding a high protein feed to your fish just before winter helps them build up fat reserves to see them through the winter but feeding a high protein diet when your fish are beginning to go into their semi-hibernation (torpor) state can be dangerous.
As your fish slow down so does their digestive system and if you feed them high protein feed they can become bloated and get constipating which is harmful and could kill your fish.
Once the temperature drops to about 5 degrees your fish will stop eating completely so you do not need to feed them at all. If the temperature hasn’t dropped that much but you see food floating on the surface it a sign that your fish have stopped eating so stop feeding.
As long as the water quality of the pond is good, and they have a good supply of oxygen your fish should survive the winter months.
If you clean your pond at the end of the autumn or the start of winter the water quality should be good enough for your fish to make it it through the winter.
Make sure to remove any leaves and organic debris that drop into your pond as soon as possible, if they are allowed to sink to the bottom they will decompose and cause harmful gasses which will be released into the water.
Leave your pump and filtration on during the winter to ensure the water is agitated and waste is removed from your pond which prevents water pollution.
If you have an in-pond pump that sits on the bottom of your pond raise it up on some bricks so you are not circulating the warmer water at the bottom of your pond also reduce the flow by about 50 percent.
Reducing the flow rate will stop too much movement in the water which may affect your hibernating fish at the bottom of your pond and as cold water holds more oxygen than warm water the circulation of the water is not needed as much during the winter months.
Turn off waterfalls and fountains if they start to ice up. Waterfalls can be run all year round and can look very nice with icicles hanging of the edges but if it gets really cold the water could freeze solid and cause a dam.
If a dam is formed on a waterfall the water will overflow over the edges and not into your pond and it won’t be long before your pump empties your pond.
Consider using a pond net is you need to protect your pond from predators and any falling leaves.
What happens if the pond freezes over will my fish survive?
If your pond freezes over your fish will have a hard time surviving unless some measures are taken.
If the surface of your pond is completely covered in ice the harmful gasses in the pond won’t be able to escape and if they build up they will kill your fish.
You also have the problem of no oxygen being able to enter the pond which your fish needs to survive.
To help your fish you need to keep an area of the pond clear of ice. There are a few things you can do to keep ice forming in an area of your pond.
Floating objects on the ponds surface like balls can help to stop your pond freezing as they bob about stopping ice forming. A pond heater is a great idea to keep an area clear of ice.
If your pond has completely iced over do not try and break the ice as this causes shock waves through the water which will affect your fish.
What you need to do is melt the ice slowly, do not pour boiling water on the ice as the hot water will mix with the pond water raising the temperature, instead use a hot water bottle or a pan of hot water and place it on the ice until it melts but make sure you remove it as soon as the ice has melted.
You need to have a hole of about 12 inches (30 cm) in diameter but if you notice your fish swimming near the hole it means they are looking for oxygen so the hole needs to be bigger.
Pond fish are very hardy and can survive water temperature as low as 0 degrees so as long as your pond doesn’t freeze solid your fish will easily survive the winter, just follow the tips above and everything will be fine, your fish will emerge in the spring healthy and active.