Pond Boss Forums AQUATIC VEGETATION Balance of plants in the environment Triploid Grass Carp, how many?

Hi all,
Since I am having a losing battle with curly-leaved pond weed, and it is growing in rather thickly and to great depths, I have decided to try out some grass carp to "trim the bushes".

It is unfortunate since I wanted pond lilies, but bringing the pond lilies into the pond in the first place brought this issue on. However I don't want my pond to become choked out and thick with this weed.

What I am attempting to do is get the right amount of grass carp to maintain the current level of plant life, not to reduce it, but keep it where it is right about now. That means I would rather understock then overstock. I want plants for a decent balance and natural cover.

I have been approved for up to 8 fish for my ~1/2ac pond, but I am thinking 3 or so may be better. I have roughly 25% coverage of CLPW right now and growing.

Any recommendations on the quantity I should apply?

I know some people have regretted adding them, looks mostly because they were overstocked so they threw the balance off.

Thanks.

Hey squid,

I think your on track. I would start out at 3. Just make sure they are big enough so they don't get ate. I put 7 in my 1 acre pond and I have only seen 4 of them those 4 were 12 inches long the other 3 were only 6 inches long and I think they ended up being lunch for my LMB. They ones that made it are quite large though at this point and they are only 3 years old. They seem to be doing an ok job.

I would not expect results though until next year. Seems it takes them a year to get going and keep the weeds down.

RC

GC are one of those things that either you have too many of them and all the weeds are gone or you don't have enough and wonder if they are present at all. It is very difficult to find a happy medium with GC.

If it were me I would skip the GC and use pond dye late in the fall prior to ice up and then freshen it up again in the spring at ice out. Curly leaf pond weed likes to start growing when the water is still relatively cold right after ice out when the water is still too cold to use herbicides. Plant growth is like a three legged stool, plants need nutrients, light, and the right temperature to take off and grow. Take any one of those three away and they won't do well. Limiting the available light for photosynthesis with a conservative amount of pond dye is probably the easiest way to limit plant growth in your pond.

While plant dye may work to limit the CLPW, it will limit all of the microscopic plants also, which are the base of the food chain. I don't feed my fish, so I worry how that would possibly limit the ponds capability. Also I am not fond of the dye-look, sort of looks fake to me.

Yet another option is to nuke from orbit (via chemical action) and start from scratch plant-wise, I have given that thought also.

I am leaning towards grass carp simply because it is a natural way to capture those pond nutrients, and let some plants live on yet limit the growth rate of the existing plants.

If I were at the 80% mark of coverage, then getting a balance would likely be next to impossible, but I think I have a shot at my lower coverage of keeping it there. Only time will tell I guess.

I am not a big fan of pond dye either but did use a small amount on my pond at ice out this spring. I have milfoil in my pond and had 9ft of visibility at ice out this spring with small patches of milfoil starting to grow on the bottom in 9ft of water this spring. A used conservative amount of pond dye to reduce the the water clarity down to 36"-42" and the resulting slow die off of the deeper milfoil triggered an algae bloom which further reduced the water clarity. Basically I steered the nutrient load towards a bloom before the milfoil could utilize most of the available nutrients. Use too much pond dye though and you are right, you won't have a good bloom.

As far as the GC go we stocked 70 triploids in my dad's old 10 acre pond to work on the milfoil and they never did make bit a difference in the amount of milfoil present. We ended up chemically treating his pond every year once the water temps warmed up enough, by then it was a mess, milfoil starts actively growing in cold water temperatures too. My experience with GC is either you have too many of them and no weeds, or not enough of them to make a difference. A smaller body of water might be different.

Years ago when I fished Smithville in MO they had put up wire cages in many areas to protect the aquatic vegetation from GC, the non-triploid GC had stripped the lake bare of aquatic vegetation and it was having a negative effect on fish populations at the lake.

Personally I think aquatic vegetation is some of the best fish habitat there is but like with a lot things having too much can be a bad thing.

I'm one of those you referred to as having regretted adding grass carp. I hate them. The last time I stocked them was in 1990, so that today they have to be at least 24 years old! I was able to shoot and kill a couple of them, and some died a natural death. But, don't believe the bunk about their lifespans being 15 years! To this day I can't get a plant to grow in my pond! The color of the water in summer time is an ugly, murky green from phytoplankton. Who knows how many GC are still alive? Sometimes I see schools of 8 or more at a time.

For you, maybe just 3 would do the trick, but I wouldn't add anymore than that. Also, I would be patient. The reason I overstocked my pond with GC was I didn't see results quickly enough. When I did see results, it was too late.

Good luck with the curly pond weeds!

CLPW is sensitive to Fluridone. It will die at lower PPB than what is needed to affect most other plants (European Water Milfoil is another plant that is affected by low doses of Fluridone).

You could hit it with Fluridone and not stock the GC. The lilies won't be affected by the low dosage.

Bingo!

If I hit the pond with Fluridone, how long would it be before I could re-plant desirable plants again? Also how about swimming? Is it something concerning to get into the mouth and eyes?

Never mind, 5 seconds of research shows it to be benign in normal concentrations. Thanks! I will probably go this route, though it is quite expensive.

The tough part is I like greenery in the pond, but I am afraid that the CLPW is just too aggressive.

Oh wow, I hope it is a pretty low concentration! 0.6 acres average depth 9'. Any recommendations how low of a dosage will do the trick compared to recommended dosage? This is clearly into wife's permission zone. I wont be able to drain down since we swim a lot in the summer.

6-10 PPB

Recommended dosages for other plants, depending on how resistant they are to it are 45 to 90 PPB.

As long as you don't have water flow-thru the pond you're good to use Fluridone. I'd measure the pond carefully and figure out the water volume. Treat at the above rate, and hit it again in 14 days with half the initial dose to make sure that the correct amount stays in the water for the correct amount of time. If you can treat the CLPW before it forms turions, you will see better long term control. If not, save your pennies to whack it again next year, but earlier in the year.

I will need to order soon, Turions seem to form any time they feel like it. I will need enough to hit next spring also.

Darn it all to heck! I like having plants early like this in the pond. I have to get some pictures of this stuff though.

LS, I sent you a private message about the concentration.

I've had some experience with GC. Years ago I have bad Eurasian Milfoil and put in 18 in my 1-acre pond and they cleaned the pond of almost every plant. So with my fish kill pond of three years ago I am starting over. Last year I had Curley Leaf pondweed witch will die back some as it gets hot but I put in 6 GC to help. This year my Curley Leaf Pond weed is worse. I am waiting until fall to see what it looks like and will probably put another 6 GC in and watch it for another year. Since I know what 18 will do to my pond I don't want that many. These fish are very smart and getting rid of them is hard. They used to come up to my deck when I fed them. I was going to get rid of a few and I tried to spear them with a large prong on a 10 long shaft and once I tried that they never came back to feed. They were so big, probably in the 20 to 30 lb range that the first one I speared pulled the spear right out of my hand and I retrieved the spear in shallow water. I did get one more chance and speared another one and the same thing happened. Thankfully the winterkill got all of them. So I think the secrete of using grass carp is to put in a few and watch them for the season and then a few more the next year if needed. Dolly eating the bones of one of the winter kill grass carp.

after reading all the discussion here about GC, I have changed my plans to stock a few of them this summer in my trout pond. seems like unless there is a really severe vegetation problem, the GC may end up being a huge regret in the long run. going to do a bit more wait and see before I consider introducing the monsters.

its always a joy to learn from others, rather than learning from my own mistakes!

J. Monroe, Two questions... So the GC will clean up E.Milfoil? And what was your spawn like the next year?

Sorry, one more ?... I probably missed it but what was your fish kill on purpose? Not picking on you, just curious .