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We’ve had a pretty hard winter. What can I expect when the ice finally melts? | Ponds & Lakes Q&A

Q: We’ve had a pretty hard winter. What can I expect when the ice finally melts?

Q: We’ve had a pretty hard winter. What can I expect when the ice finally melts?

Kevin – Downers Grove, IL

A: Yep, this has indeed been a long, cold winter for much of the country. We’ve shivered through frigid temperatures, shoveled and slogged through snow banks, and watched our ponds and lakes freeze over.

Unfortunately, that could mean trouble for your fish.

When the ice on your pond finally melts this spring, you might discover that your fish and other aquatic life haven’t survived the season. These winter fish kills occur when the ice prevents gas exchange and reduces the amount of dissolved oxygen in the water.

Michigan DNR fish production manager Gary Whelan says that shallow lakes, ponds and streams are particularly vulnerable to winterkill.

“Winterkill begins with distressed fish gasping for air at holes in the ice and often ends with large numbers of dead fish that bloat as the water warms in early spring,” he explains. “Dead fish and other aquatic life may appear fuzzy because of secondary infection by fungus, but the fungus was not the cause of death. The fish actually suffocated from a lack of dissolved oxygen from decaying plants and other dead aquatic animals under the ice.”

You can’t bring your fish back to life, but you can prevent winterkill from happening in the future by aerating your pond year-round with an Airmax® Pond Series™ Aeration System. Here’s how it works:

  • It reduces the amount of decomposing debris in the pond, encouraging the colonization of beneficial aerobic bacteria, which prevents muck and nutrient accumulation and maintains clear water.
  • It keeps an air hole open in the ice, allowing harmful gases to escape while delivering fresh oxygen to your fish.
  • It pumps even more fresh oxygen into the water via diffusers that sit on the bottom of the pond.

A little pond preparation can go a long way, especially when it comes to unknown variables like weather. Let’s hope next winter is milder than this one was!

Pond Talk: Have you experienced a winterkill in your pond or lake before?

Airmax(r) Aeration is Easy to Install - Airmax(r) Pond Series(t)

I heard you can lose fish during the winter. How do I prevent a winter fish kill? | Ponds & Lakes Q&A

Q: I heard you can lose fish during the winter. How do I prevent a winter fish kill?

Q: I heard you can lose fish during the winter. How do I prevent a winter fish kill?

Jon – Little Suamico, WI

A: Imagine being cooped up all winter long in a room with no ventilation and no fresh air. Pretty claustrophobic, right? Now add the stench of decaying garbage and other waste buildup … it’s likely you wouldn’t last until spring.

It’s a similar situation with your fish.

In colder climates that freeze over the winter, decomposing vegetation and waste beneath the ice layer releases toxic gases that build up, displacing the oxygen that the fish need to survive. When that O2 is replaced with ammonia and other harmful gases, the result can be a winter fish kill.

So how to do you prevent this from happening? Aeration with an Airmax® Aeration System.

Open a Window!

An Airmax® Aeration System sized for your lake or pond moves the water below the frozen surface, which keeps an air hole open in the ice. This ventilation allows the harmful gases to escape while bringing in fresh oxygen for your fish. The aeration also injects oxygen into the water via the bubbles that come out of the diffuser or air stones.

Provide Year-Round Oxygen

For the health of your fish, we recommend you run an aeration system year-round—unless you plan to use the pond for winter activities, like ice skating or hockey, that require a solid and safe sheet of ice. In that case, follow the instructions in your product manual to safely turn off your system.

Create a Warm Zone

If you plan to run your system year-round, move the diffuser plates into shallower water during the winter months. This will allow your fish to hunker down in your pond’s warmer depth for the winter. It will also prevent the rare “super cooling” effect, in which the water temperature dips below freezing and over chills your fish.

Pond Talk: Have you ever experienced a winter fish kill? What changes did you make to prevent it from happening again?

Aerate Your Pond in All Seasons - Airmax® Deep Water Aeration

When should I switch my fish food and what should I use? – Decorative Ponds & Water Gardens Q & A

When should I switch my fish food and what should I use?

When should I switch my fish food and what should I use? Millie – Mayday, GA

Better Pack a Cold Lunch

As the temperatures begin to cool down at the end of the year you will notice a change in the behavior of your Koi and Goldfish. Your fish will start to slow down and become less active as the water gets colder as they prepare for a winter of dormancy. You will still want to feed your fish in these cooler fall temperatures. A change in diet will help maintain happy and healthy fish and prevent potential fish kills going into the winter.

A decrease in activity means that your fish are slowing down and this is not just in regards to the energy level but to their bodily functions as well. Your fish will still be hungry and want to eat but because their digestive system slows down they will require less food and will take longer to digest what you’re feeding them. This can be problematic if you continue feeding your fish heavy high-protein foods in the cooler seasons. Excess food that has not been digested can begin to rot inside the fish before they can excrete it as waste causing illness and even death.

Fish food containing wheat germ like Pond Logic® Spring & Fall Fish Food are designed for colder weather feeding. Your fish have an easier time digesting these types of food at low temperatures which will keep them full and happy without putting them at risk. Knowing what types of food to use in colder temperatures is important but when do you make the switch? When your water temperatures fall between 40-50 degrees Fahrenheit you will want to start feeding with your Spring & Fall food. The best way to monitor the temperature of your pond is to use a Floating Thermometer and watch your fish for decreased activity. If they tend to just stay at the bottom of the pond and are not interested in eating before the water temps dip below 40 degrees then you can stop feeding early. Food that is left to sink to the bottom of the pond will turn into muck and aid in algae blooms come early Spring. If your fish are still active and eating you can feed them Spring & Fall food until the water temps fall below 40 degrees. During the winter your fish will just relax at the bottom of the pond in a state of dormancy until the water temperatures warm back up in the Spring.

POND TALK: What signs do your fish give that tell you they are getting ready for winter?

Get your fish ready for winter!

Why Did My Fish Die Over the Winter? – Pond & Lake Q & A

Illustration of No Aeration Versus with Airmax Aeration

Pond & Lake Q & A

Q: I lost all of my fish after the winter. We love to catch fish in the pond and now we have to start over! What happened? And is there anything I can do to prevent this from happening again? – Alfred of Michigan

A: My first thought when I read this question was, “They don’t have an aeration system”. And after speaking with him, come to find out, he didn’t. This is usually always the case during a winter fish kill. Everything seems to be going just fine when all of a sudden one morning you wake up to discover a wave of fish floating on your pond’s surface. This is not a pretty sight, nor is it any fun to clean up. So what causes fish kill and what can you do to prevent it?

What Causes Fish Kill?
During the warmer months of the year a pond with no aeration will contain oxygen towards the surface of the pond. This is because there is an oxygen transfer from air to water at the pond’s surface. The bottom of the pond, however, will contain very little or no oxygen; Certainly not enough to support fish life. Also, the toxins associated with fish waste and other organic biodegradation tend to sink and stay at those lower depths of the pond, polluting the already oxygen-starved water. This unfortunately, condenses your fishes’ habitat area and forces them to live towards the surface of the pond.

There is also a difference in temperature from the bottom of the pond to the surface. The bottom of the pond will be colder than the pond’s surface. The reason for this is because the sun will heat up the surface of the water and since cold water is denser than warmer water, the cold water will fall to the bottom. This difference in temperatures can be quite dramatic at times. Have you ever jumped into a pond and felt the brisk cold water towards your feet? This is the thermocline border. This dramatic change in temperature can cause your fish to stress as they travel from a warm temperature to a cold temperature and back to warm. This stress can lower their immune systems.

During the colder months of the year, the oxygen as well as the thermocline will actually flip. All of a sudden the colder water containing no oxygen will mix with the warmer water with oxygen. As this mixing occurs, the fish are left with few places to go for oxygen and they will eventually suffocate.

Another issue during the winter are toxic gasses. As bottom organics (grass clippings, leaves, trees, twigs, fish waste, etc.) decay, they will create toxic gasses. When ice covers the pond’s surface, these toxic gasses are trapped underneath the ice and will cause a fish kill.

Preventing Fish Kills
Using an Airmax Aeration System is the single most important way to help prevent winter fish kills. The reasons are simple: With an Airmax Aeration System, a compressor sits on shore and pumps air down to a diffuser on the pond’s bottom. This air forces the cold water containing no oxygen to the pond’s surface. This water, because it is denser, will fall back to the pond’s bottom. This cycle will repeat and create a convection or current within the water column. This will fill the whole water body with oxygen as well as maintain the same temperature level throughout the pond (see illustration on left).

Also, during the winter months, when ice has covered the surface of the pond. An Airmax Aeration System will keep a small hole open in the ice to allow those toxic gases to escape.

The Bottom Line: Having aeration will help reduce the chances of fish kill. Also, remember that this is one of many benefits of having an aeration system (Refer to this blog post for the other benefits of aeration).

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