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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® Pond Series™ Aeration

I think I have duckweed or watermeal. How do I know? And how do I treat it? | Ponds & Lakes Q&A

Q: I think I have duckweed or watermeal. How do I know? And how do I treat it?

Q: I think I have duckweed or watermeal. How do I know? And how do I treat it?

Richard – Fishers, IN

A: Duckweed and watermeal are both pond pests. Dense colonies of these prolific plants can completely cover the surface of a lake or fish pond, causing dissolved oxygen depletions and fish kills. These tiny invaders need to be managed before they take over.

But before you control them, you need to get to know them. Let’s meet these troublemakers.


The smallest seed-bearing plants in the world, watermeal is a very tiny (less than 1 millimeter) light green free-floating rootless plant that resembles green cornmeal. They prefer quiet water that’s undisturbed by waves, and they’re often associated with colonies of duckweed and mosquito fern (azzola). Unchecked, these plants can be aggressive invaders.


Duckweed is another very small light green free-floating plant, but unlike watermeal, duckweed has a single root and one to three leaves, or fronds, that measure 1/16- to 1/8-inch long. Like watermeal, duckweed tends to grow in dense colonies in quiet water that’s undisturbed by wave action. Duckweed colonies provide habitat for micro invertebrates, but if it completely covers the surface of a pond for an extended period, it will cause oxygen depletions. As its name implies, duckweed is often gobbled by ducks, which also transport it to other bodies of water but you cannot count them for keeping the weed in control.

Stop the Invasion!

To control these aquatic bad guys, you’ll need a herbicide. Clipper™ and Ultra PondWeed Defense® are both selective plant killers that will attack watermeal and duckweed. They’re a short-term solution for both—be sure to apply as directed.

For long-term control of duckweed, you’ll need something a bit stronger. We recommend Sonar™ A.S.. It’s formulated to control stubborn aquatic weeds all season long. Don’t forget to add pond dye, it protects the Sonar™ A.S. from being quickly degraded by the sun.

Pond Talk: Tell us about your experiences with duckweed and watermeal. Do you have any additional management tips to share?

Deliver Fast & Selective Control Of Weeds - Valent® Clipper™ Aquatic Herbicide

What Is A Winter Fish Kill & Why Do They Happen? | Ponds & Lakes Q&A

What Is A Winter Fish Kill & Why Do They Happen?I’ve heard the term “winter fish kill.” What is it and why does it happen?

Linda – Stockbridge, MI

A winter fish kill occurs when your pond or lake becomes uninhabitable for aquatic life and a large number of fish pass away. Winter is the most common time for a fish kill because the long, harsh conditions of the season deplete the oxygen content of the water.

Prolonged ice cover on your pond or lake seals off the water from the air and prevents oxygenation of the water. Ice and snow cover also prevent sunlight from reaching your pond plants. Pond plants normally produce extra oxygen for your pond via photosynthesis. Finally, decomposing organic matter in your pond releases toxic gases that can’t escape from under the ice.

Eventually the competition for the limited supply of oxygen in the pond becomes too great. The fish suffocate and a winter fish kill occurs.

The good news is that winter fish kills are preventable. There are many things you can do as a pond and lake owner to maintain proper oxygen levels in your pond. First and foremost, invest in a good Aeration System. Aeration is the process of circulating air through water and it’s critical for overall pond health.  A second option is to add beneficial bacteria products like MuckAway™ or PondClear™ to your pond or lake before the winter season. Beneficial bacteria digest accumulated decomposing organic matter in your pond and convert it to a harmless, odorless gas.

Pond Talk: What fish behavior may indicate low oxygen levels in your pond?

Airmax® Aeration Systems

My pond isn’t frozen yet, but I can’t see my fish. Are they okay? | Ponds & Lakes Q&A

My pond isn’t frozen yet, but I can’t see my fish. Are they okay?

My pond isn’t frozen yet, but I can’t see my fish. Are they okay?
Stephanie – Harpursville, NY

Fish are survivors. And when the water starts getting cold, they head for deeper waters, where the chilling effects of winter air are less pronounced. Provided there’s adequate aeration, your fish will likely linger at the bottom throughout the colder months. As a result, they’ll be much less visible – but the odds are extremely good they’re doing just fine.

In order to ensure there’s sufficient oxygen for the winter, some people opt to keep their aeration systems active all year ‘round. At the very least, though, it’s important to maintain a vent hole when – or if – your pond ices over. The vent hole allows harmful decomposition gases to escape, allowing fish to winter safely. And because their metabolism slows during the winter months, a properly vented pond will likely have sufficient oxygen to ensure the survival of your fish until springtime.

Fish, it turns out, are extremely resilient. After wintering in the lower reaches of your pond, your fish will gradually return to the upper levels once water temperatures start to rise. In general, it’s probably a good sign when fish become less visible. If they’re struggling, it’s far more likely you’d see them at the edges of your pond. So while you might miss them, your invisible fish are probably doing just fine.

Pond Talk: Have you noticed less fish movement in your pond recently?

Do herons fly south for the winter? | Ponds & Lakes Q&A

Do herons fly south for the winter?

Do herons fly south for the winter?
Bobby – Milwaukee, WI

Herons are migratory birds, and they have no appreciation for cold weather. So if you’re located in the cooler northern climes – particularly where ponds tend to freeze during the winter months – you’ll usually notice their absence when temperatures start to drop. Like many of us would like to do during winter, herons that choose to migrate will head for Central America and northern South America to warm up and fill up on fish. If you live in warmer portions of the United States, however, you may see herons all year ‘round, provided there’s enough open water and food to keep them happy.

While they’re beautiful to watch, herons are often unpopular with pond keepers – particularly those who have stocked their pond well. Herons consider fish as their favorite snack, and a single bird will happily devour every available fish, leaving the pond empty, and the pond’s owner grumpy. Herons aren’t picky eaters, though, and they’ll also snack on feeder fish, frogs, salamanders, lizards, snakes, grasshoppers and even dragonflies.

Fortunately, herons don’t hunt in flocks. When they spot a pond that’s already been claimed by another enterprising heron, they’ll typically fly elsewhere. That’s why we strongly recommend our Great Blue Heron Decoy as a simple way to discourage hungry herons from settling in for an uninvited visit.

Without preventative measures – like a well-placed and regularly relocated decoy – a heron will settle in as long as food is available. Otherwise, only cold temperatures, which send fish to the warmer water layers at the bottom of the pond and other food sources to their winter lairs, will encourage a heron to move on.

Pond Talk: Do herons continue to visit your pond throughout the fall and winter or more on?

Pond Logic® Blue Heron Decoy

My Fish Are Nibbling At My Toes When I Swim. Why Is This Happening And How Can I Stop It? | Ponds & Lakes Q&A

My Fish Are Nibbling At My Toes When I Swim. Why Is This Happening And How Can I Stop It?

My Fish Are Nibbling At My Toes When I Swim. Why Is This Happening And How Can I Stop It?

Holly – Wiggins, CO

While we love hand feeding our fish from time to time, nothing ruins your day faster than taking a dip in your cool refreshing pond water only to be reduced to an overgrown chew toy. No one wants to swim in a pond where they feel they may be next one the menu, so how do you stop your touchy feely finned friends from taste testing you and your friends?

It is common to have the smaller prey fish in your pond try to make a quick meal out of your fingers and toes than their larger predator counterparts. It is a sign that your pond may be imbalanced, creating a shortage of food for your smaller fish. They are simply trying to find a snack wherever possible and that includes your precious phalanges. Keep tabs on your fish population to make sure you have a balanced ratio of 3 prey fish to every predator.

If you have an abundance of smaller fish in the pond you may want to introduce some minnows into the water to give them a quick and easy meal that can be replenished over time. If your pond does have an unbalanced population, investigate why this may be. Make sure you have adequate habitat in the pond for your small fish to hide and mature and if you feel your fish are having trouble finding enough food consider manually feeding them using a quality fish food like Game Fish Grower Fish Food.

If you are not quite sure what or how to feed your fish read our Fish Food Blog. Also for some great tips on adding habitat to your pond click over to our Creating Habitat Blog.

Pond Talk: Do your fish nibble at you when you swim in your pond?

The Pond Guy® Game Fish Grower Fish Food


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