Ross, I hear of many folks who've had bad experiences with grass carp. Overstocking is a real risk, and it is so tempting when you look at a pond or lake covered with weeds.
I got permission to stock grass carp, but hesitate to do so. Once used herbicide which was effective, though I prefer not to use chemicals. Tough call!
Grass carp are never an issue. But, a pond owners incorrect stocking of them can be a really big issue.
I would never stock GC at a rate that eliminated the targeted plant. If the GC do their job, then the potential for turbid water is extremely high. Think control, not eliminate. I currently have 120 GC in my big pond, and the water's clear as a bell. The initial stocking was 50%(60), and then another 20 were stocked every other year. So it took 6 years to complete the stocking. Ladder stocking does 2 things. One, it let's you reevaluate every 2 years, so stocking can stop if everything's going well. And two, as the older GC slow down their consumption, the younger GC will take over.
Think Goldilocks and the 3 bears. If you don't stock enough, then problematic plants won't be controlled. If you stock to many, then by the second year, you could be dealing with a turbid pond that's extremely difficult to correct. If you do a proper evaluation, get a permit(if required) for the correct amount of GC, and ladder stock those GC as needed, then everything should be just right.
Grass Carp Preferences
