Grass Carp

Species Name

Ctenopharyngodon idella

Fast Fact

The grass carp is the species with the largest reported farmed production globally, exceeding five million tonnes per year

origin

Originating from the Pacific Far East, the grass carp is a large freshwater herbivore native to regions stretching from northern Vietnam to the Sino-Russian border. Initially cultivated for centuries in China as one of the "Four Domestic Fish," it was later introduced globally for aquatic weed control, becoming the most extensively farmed fish species worldwide

diet

Primarily feeds on aquatic vegetation, making it useful for controlling weeds in water bodies. However, its introduction can disrupt ecosystems by altering habitat structure and impacting native species. While it can help control algae, it may also contribute to nutrient cycling issues and algal blooms, posing risks to water quality and safety.

lifespan

Grass carp lifespan ranges 10 to 20 years in the wild, depending on factors such as habitat quality, predation, and availability of food resources. In captivity, they may live slightly longer, reaching up to 20 to 25 years under optimal conditions.

size

The grass carp reaches a typical length of 60–100 cm (24–39 in) with a maximum length of 2.0 m (6.6 ft) and weight of 45 kg (99 lb)

Background

Grass carp have been introduced to numerous countries worldwide, with notable introductions in both the Northern and Southern Hemispheres. While they have established self-reproducing populations in only six major Northern Hemisphere rivers, their specific reproductive requirements limit their success in other waterways. In the United States, grass carp were first imported in 1963 and subsequently introduced to numerous states, primarily for biocontrol of aquatic vegetation. Despite widespread stocking, their reproductive presence was confirmed in the Great Lakes Basin in 2013, highlighting ongoing concerns regarding their impact on local ecosystems.

Physical Description


The grass carp exhibits an elongated, chubby, torpedo-shaped body, with a slightly oblique terminal mouth featuring non-fleshy, firm lips and no barbels. Its lateral line comprises 40 to 42 scales, and it possesses broad, ridged pharyngeal teeth arranged in a “2, 4-4, 2” formula. Sporting eight to 10 soft rays, the dorsal fin and anal fin are set closer to the tail than typical for cyprinids. Its body showcases a dark olive hue, transitioning to brownish-yellow on the sides, complemented by a white belly and large, slightly outlined scales.

Preferred Habitat

Grass carp inhabit a variety of freshwater habitats, including lakes, ponds, pools, and backwaters of large rivers. They prefer environments characterized by large, slow-flowing or stagnant water bodies abundant in vegetation. In their natural habitat, grass carp spawn in fast-moving rivers, where their slightly heavier-than-water eggs drift downstream, suspended by turbulence, for development. Survival of the eggs and young fish requires long rivers, as the eggs are believed to perish if they settle at the riverbed. Adults primarily feed on aquatic plants, including both higher aquatic plants and submerged terrestrial vegetation, along with detritus, insects, and other invertebrates. They have a voracious appetite, consuming up to three times their body weight daily, thriving in environments with ample vegetation.

Controlling the population

Grass carp are renowned for their impressive size and strength, posing a formidable challenge to anglers when hooked. However, their vegetarian diet and cautious nature make them elusive targets for traditional fishing methods. The IGFA World record for a grass carp caught on line and hook stands at 39.75 kg (87.6 lb), exemplified by a catch in Bulgaria in 2009. Additionally, grass carp are sought after as sport fish in regions where bowfishing is permitted. In areas where grass carp are stocked for weed control, anglers are typically encouraged to release any caught fish back into the water unharmed to maintain population balance.

Images

Historical Occurence

Invasive Carp

Grass
Black
Bighead