Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Pros and Cons of Grass Carp

Dave, my pond is around 6-7 acres. I'm most likely going to start w/ only (10) grass carp. I know that sounds low.

I don't want total elimination of the weeds.

From there, I'll gauge progress and adjust as necessary.

Thanks for the input.

Tim K. ,
What kind of vegetation do you have in your ponds that the carp eat? Was it eurasian milfoil?
Dave Davidson, what kind of weeds were in your neighbor's one acre pond?
I have a milfoil problem I'm going to address with grass carp . Can't afford chemicals, and raking it out is not practical.
When is the best time of year to stock 11-13" grass carp? Would it hurt to stock them in the fall in North Central Texas?
Thanks in advance.

We were dealing with American pondweed and some millfoil.

BTW, I just bought that 71 acre place. It is contigous to my original place. Now I have to get my butt over there and spray some small willows and catch a bunch of 10 inch bass. We stocked the grass carp in the summer. They have really clobbered the vegetation. I caught one of them on a small hook with a piece of night crawler the other day. I guess they are getting hungry. I was bluegill fishing and got a heckuva fight on my ultralight. It was about 18 inches long and had doubled it's size in a year. They definitely work.

It is feb 20th been cold in tennessee. I have had some algae in the past spray chrystal plex and it is gone quick. Pond is around .5 acre this bloom is bad. Sprayed today would you guys add a grass carp or 2 to the pond? I feed everyday and I have heard they just eat you pellets and so nothing would 2 help?

GC don't eat algae. Now, if you can stock Tilapia after it warms up enough, they'll eat your algae.

I second the Tilapia. Some states don't allow them though. GC won't eat FA unless it's the only thing left in the pond. They will eat pellets, but go buy some Stubby Steve's pellets, catch them if you see them eating pellets and they will learn to stop eating them. You might have to refresh their memory once a year. The problem is that if you want to get some underwater weeds established, you can't with them in the pond.

Since grass carp eat submerged plants, but don't eat filamentous algae unless they are literally starving, it seems like grass carp would be CONTRA-INDICATED for ponds with FA problems?

If the FA and the submerged plants somewhat compete for nutrients, and FA is by far the worst problem in the pond, then it seems to me a pond owner would have better net results by removing all of the grass carp.

However, I don't recall ever seeing that advice starkly stated on Pond Boss.

Am I wrong in my non-expert evaluation of the pond dynamics?

(P.S. If your pond results are worse after removal of the grass carp, you can always add a few back in.)

I realize this is a 20‑year‑old thread that just got dragged back to life by Langster, but since we’re talking grass carp, here’s my experience from up here in NY.

Around here, the DEC decides how many GC you’re “allowed” to have, which sounds like control… until you realize you actually have no control. They told me 12 for my one‑acre pond. Since they’re a bit pricey in NY, I went with 8 and figured I was being clever.

At 12–14 inches, those little torpedoes eat like they’re training for competitive food‑eating. I was thrilled — weeds disappearing, no chemicals, and I’m thinking I’ve cracked the code.

Fast‑forward a few years… weeds start creeping back. Meanwhile, my GC are now 2‑foot submarines lazily cruising around like retired tourists on a riverboat. You’d think something that big would be mowing down vegetation just to maintain its waistline, but nope. Apparently once they hit “big and impressive,” their metabolism clocks out.

So, another permit, another batch — this time I get 10. They go to work immediately. Weeds vanish again. And then… all weeds vanish. Great for the swimming area, not so great for the fish habitat. The pond looked like a freshly vacuumed carpet.

At this point, I’m rethinking the DEC’s magic numbers. Not sure what the perfect count is, but I do know those carp absolutely nuked the place. Maybe once this batch bulks up and slows down, things will settle into a happy medium where I can have some weeds without the pond turning into a salad bar.

10X is spot on with his analysis. We had 400 triploid GC introduced in 2012 to clean up American Pondweed on our 54 acre lake. Those, now huge, knuckleheads are still cruising around. They are 30" & 20-25 pounds but highly unproductive...My suggestion when considering GC, less is better, you can always add more down the road if needed...They are fun to catch. When we do catch one, the rest of the herd will avoid that area of the lake for months. They are a smarter fish than people realize!