For the first time I believe - We have duck weed in our pond. It's stocked with fish.

Harmful? Should we try and remove it?

If so - What is the best way to remove/control it?

If part of the plant is above the surface, you'll probably have success using Diquat. (2-3oz/gal in a pump sprayer). You probably need to use a boat to reach areas away from the bank. I treat my ponds routinely and Diquat seems to kill everything above water. I buy mine from Solutions Store.com. It's $23-30 cheaper than Amazon.

Texas AgriLife has a website that you can ID your aquatic plant and determine what chemicals will manage them.
https://aquaplant.tamu.edu/plant-identification/

Thanks! Hmm ok to use with fish? Also have horses that drink from the pond…

I have a couple aquariums with duckweed. It looks identical to the plant in your photo.

It's beneficial in aquariums / helps clean ammonia and nitrates out of the water.

The downside is that it multiplies rapidly and once it's in a tank, you can't really get it out.

For a pond… if allowed to form a mat, it will block sunlight from reaching down into the water column. That can create a no-bueno situation that impacts fish.

Some of that is Wolffia (watermeal). Too much of duckweed/watermeal can cause oxygen depletion in hot summer. Fluridone (Sonar) liquid will smoke it but expensive.

Spraying it and killing it will deplete the oxygen in the pond = dead fish.....especially with hot summer temps.

Stock tilapia in the pond. They eat duckweed, mill weed and other floating plants.

They also breed prolifically and act as a bait fish for bass and catfish.

They are fun for kids to catch on a worm.

They will die in the winter and need to be re-stocked every spring.

Get some ducks??