Q: What are winter fish kills and how can I prevent them? – Alison in Illinois

Winter Fish Kills, They Don’t Float With Us!
You’ve waited all Winter long for the ice to melt over your water garden so you can run your waterfalls and enjoy your finned friends. Instead, you find your fish floating at the ponds surface, victims of a winter fish kill. What is this phenomenon and how can you prevent it?

Make Some Holes
When a layer of ice forms over the surface of you water garden, it essentially eliminates any transfer of air to or from your pond’s water. What this means to you is that, as debris decompose and your fish consume oxygen, byproducts are produced in the form of gasses that are toxic to your pond’s inhabitants. These gases are trapped under the ice and cannot escape; fresh air from outside the pond cannot reach the water either and so begins the process of the winter fish kill. Keeping a hole in the ice will allow the bad air in the pond to be replenished with good air. Some pond guys and gals use pond De-Icers to maintain an open hole, but many more rely on their aeration systems to do the job.

Pass The Bubbly
We’ve discussed in our past blogs the many benefits of aeration in your water garden. It circulates the water in your pond, infusing it with oxygen which is beneficial to your bacteria and fish. The constant bubbling produced by an aeration system will also keep a hole open in your water garden in the winter months, ensuring the release of those harmful gasses.

Being Supercool is SO Uncool
You have all heard concerns expressed in our past blogs in regards to “supercooling”. While this is a rare occurrence, there are a couple steps you can take to ensure you don’t overdo your winter aeration. When the cold weather comes, move your aeration plates to a shallower part of your pond. This will maintain a warmer layer of water for your fish to retreat to if the water does get a little too chilly. Furthermore, if you have a multiple plate system, you can run your water garden on just one plate for the winter. This will ensure that you have an open hole in your ice and should provide sufficient air supply to your fish as they require less oxygen during these times of decreased activity.

POND TALK: What type of aeration do you use in your pond? How have your fish fared over the past winters?

Nope, frogs don't turn to stone in the winter.

Water Garden & Features Q & A

Q: What happens to my frogs in the winter? – Sue in Michigan

A: They ribbit and hop in your pond all spring, summer and fall, but when the cold weather comes, your frogs seem to disappear. Don’t worry – they don’t croak! They simply take a long winter nap.

There are more than 5,000 described species of frogs living on just about every surface of the planet. From the frigid Arctic Circle to the hottest deserts and everywhere in between – including your back yard. These welcome additions to any pond have evolved a well-known strategy to survive environmental extremes: They hibernate. Frogs that live in temperate climates with cold winters, like those throughout much of the United States, enter into a dormant state of sleep while living off their body fat reserves.

Aquatic frogs, like the leopard frog and the American bull frog, typically hibernate underwater. Because their skin can absorb oxygen, they lie just below the surface among aquatic plants where they’ll be safe from predators and frosty temperatures. An aeration system will add oxygen to your pond and create a hospitable habitat for your amphibian friends – and your finned friends, too.

Terrestrial frogs, like American toads, will hibernate on land. The ones that can dig will create a comfortable burrow beneath the frost line and sleep all winter; the ones that can’t dig will find safe hiding places, like hollowed-out logs, between rocks or beneath a pile of leaves, to protect them from weather and predators. Incredibly, these frogs won’t freeze to death; though they may partially freeze in very cold climates, a high concentration of glucose in their organs prevents them from freezing completely. When spring comes, the frozen portions thaw and they’re ready to get back to eating and reproducing.

Frogs are just one of dozens of critters that are drawn to water features. By providing a habitat with food, water and shelter, you can draw wildlife to your pond – which will enhance your enjoyment of it even more.

POND TALK: Do you have frogs in your decorative pond?

Gasping Koi

Water Garden & Features Q & A

Q: My koi seem to be gasping for breath at the surface of my pond. Why are they doing this? – Bill in Louisiana

A: If your koi are coming to the surface of the pond to gulp for air, they’re doing more than just saying hi. They’re employing a survival strategy! Due to a lack of aeration or poor water quality, your pond’s water probably does not have enough dissolved oxygen in it for the fish to “breathe,” so they’re gasping for oxygen from the air.

This lack of sufficient oxygen can then cause the fish to stress, which then inhibits their immune systems and opens the door for parasites and disease. But you can prevent that from happening by aerating the water and keeping the water quality as crystal clear as possible.

Koi breathe by pumping water over their gills to extract dissolved oxygen from the pond water. Depending on their activity level, koi require varying amounts of oxygen. For instance, a koi’s active summer metabolism will require more oxygen; a hibernating winter metabolism will require less oxygen.

This can be a challenge during the warm summer months, when the pond’s water temperature rises. Warm water holds less dissolved oxygen, so just when the fish need it the most, it’s at a lower concentration!

To pump more oxygen into the water, you can also add plants to your pond, which naturally release oxygen into the water during the day. Your waterfall or fountain will also add oxygen to your pond. But depending on your fish load and pond size, plants and a fountain often aren’t enough – especially during the summer. That’s where an air diffuser, like the KoiAir® Water Garden Aeration Kit, can help. Powered by a silent, reliable compressor, a diffuser system will add oxygen to your pond, aerate, circulate and eliminate dead spots, keeping your pond and fish active and healthy all year long.

Because poor water quality can also cause fish to gasp for air at the pond’s surface, you should also check your filtration system, and test your ammonia and nitrite levels with a standard test kit, like the Pond Care® Master Test Kit. If your levels are high, consider adding beneficial bacteria, like Pond Logic® LiquidClear™, to kick-start your pond’s nitrogen cycle.

Once you aerate your pond and make sure your water quality is in check, your koi should stop gulping oxygen at the surface. When they do greet you at the water’s edge, it’ll be for a juicy slice of watermelon or some Pond Logic® Floating Ponstix fish food instead!

POND TALK: When you see your fish gasping for breath, what do you do?

Picture of a Water Garden in the Winter with a Bubbler Aeration System.

Q: Do I have to take my koi and goldfish out of my water garden for the winter? – Barbara of Massachusetts

A: No you don’t actually. They are many water garden owners who leave their koi and goldfish in their water garden throughout the winter season with no issues whatsoever. There are really only two things that you need to do to make sure your water garden is fit to allow fish to winter over:

Does your water garden have a depth of at least 18″?:
This is very important. There are places in the US alone where water freezing depths can easily be around 18″ to 24″. I suggest a minimum of 18″ of depth to be safe, but I am more inclined to recommend 24″ just to be double safe. We want to make sure our fish friends don’t become icicles. In either instance, it’s also extremely important to make sure we keep a hole open in the ice during these cold times, which leads me to the second thing.

Keeping an open hole in the ice during the winter:
During the winter, when the ice forms a solid layer across on the surface of your water garden, there are toxic gases, caused by decaying vegetation or organics, that can build up underneath the ice. This build up can become so toxic underneath the ice that it can kill all of the fish in the water garden. The best thing to do in this situation is to keep a hole open in the ice to allow for these gases to escape. This is actually very easy to accomplish. Using a pond heater/de-icer, such as a Pond Saucer or ThermoPond, is a great way to keep a hole open in the ice. Another way to keep a hole open in the ice would be to use a small bubbler aerator. These will not only keep a hole open in the ice, but will also add oxygen as well! Bubbler aerators can be used all year to keep oxygen levels high.

Q: Does my water garden need an aerator during the warmer months of the year? -Several Customers

A: That depends on a two things: Fish Load & Depth.

Fish Load: The greater the fish load, the higher the oxygen demand. A water garden aeration system is highly recommeded for high fish loads.

Depth: If your water garden is deeper than 24″, it is important that the water towards the bottom is also being circulated. In a skimmer/waterfall filtration system, the water will circulate across the surface of the water and leave the water towards the bottom stagnant. Adding an aeration system will prevent any stagnation by lifting the bottom water towards the surface. See our selection of Water Garden Aeration Products.