“Largemouth Bass are generally the biggest offender when it comes to eating Grass Carp.”
Grass Carp are extremely effective at controlling submersed (underwater) vegetation. Here in Florida, we are required to stock Triploid Grass Carp, meaning they can’t reproduce. However, the required testing to ensure they are sterile results in an expensive fish. Depending on the time of year and the size of the Grass Carp, they can cost between $12-$20 per fish. Grass Carp are worth the cost, but you must protect them from predators. They are not only a target for birds, like Herons and Osprey, but also other fish in your pond. Although there are ways to protect Grass Carp from avian predators, we will focus on fish in this segment. Largemouth Bass are generally the biggest offender when it comes to fish that eat Grass Carp. Largemouth Bass can swallow prey up to half their size, depending on the shape of the fish. For example, a 16” bass can swallow a wide-bodied Bluegill up to 4” long (or longer – see picture below). Grass Carp have a skinnier profile than a Bluegill, meaning this same 16” bass could easily swallow a 6” Grass Carp, a size commonly offered by Grass Carp distributers.
Bass can swallow prey 1/4 of their total length, sometimes longer. As you can see, this 8″ bass had no problem swallowing a bluegill half its size.
So, what can you do to avoid this? The easiest option is stock them in ponds without Largemouth Bass more than a foot long, but this isn’t always possible. If your pond quality bass, consider stocking larger Grass Carp. Eight to 10” Grass Carp should be safe from all but the biggest bass in your pond. However, this requires obtaining larger fish from Grass Carp distributers, which isn’t always possible either.
Short of making it known to your distributer that Grass Carp less than 6” won’t work in your pond, the next best solution is to stock higher numbers of Grass Carp in your pond. This could be as much as twice the recommended number per acre. Sure, it may cost you a few more dollars, but the reason this works is that Grass Carp grow quickly. If you can get a handful of fish to survive 2-3 months, they will quickly grow to a size too large for any bass in your pond to eat. When looking out over your weed-free pond, you will be thankful you spent a few extra dollars on the high-stocking rate.