How Fast Do Grass Carp Grow?

The grass carp, sometimes called the white Amur, has been introduced to the United States from China.

Ideal Growth Rate

Pond owners often use the fish to control aquatic vegetation. Commercial fish hatcheries have developed methods to produce a sterilized version of the fish that will not reproduce. In most situations the fish population is maintained to remove aquatic grasses and other unwanted plants. Given the proper conditions, the fish can grow rapidly.

Young grass carp grow quickly if allowed to feed in an environment with an adequate source of desired plants. In some cases, grass carp can grow at a rate of 2 pounds per month. This rapid growth rate requires a combination of warm water, adequate oxygen as well as plant vegetation. This growth rate decreases as the fish ages.

Life Expectancy

Sterilized grass carp live as long as 10 years under ideal circumstances. Female fish can reach 40 pounds as a mature weight, with male fishes slightly smaller. The non-sterilized grass carp can live 20 years or longer.

Food Consumption

The consumption rate increases as the fish grows with fish less than 6 inches in size eating about 8 percent of their body weight every day. By time the fish is about 2 pounds in size, it consumes its weight in grass every day. Peak consumption occurs in fish between the weight of 2 pounds and 10 pounds where consumption drops off to about 25 percent of the fish's body weight. The fastest growth occurs during the periods the fish is consuming the most feed.

Temperature and Growth

Grass carp tolerate cooler temperatures but consume less food and grow slower. Water temperatures below 50 degrees result in inconsistent feeding. The highest rate of feed consumption occurs when water temperatures are between 70 and 86 degrees. The warm temperatures not only result in greater grass consumption but in higher growth rates.

About the Author

Keith Allen, a 1979 graduate of Valley City State College, has worked at a variety of jobs including computer operator, medical clinic manager, radio talk show host and potato sorter. For over five years he has worked as a newspaper reporter and historic researcher. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines.