Mrigal

The mrigal is a freshwater carp native to the river systems of the Indian subcontinent, including the Ganges and Brahmaputra basins, and is one of the three classic Indian major carps farmed alongside catla and rohu. It has a more slender, streamlined body than its farmed relatives, with fine silvery scales and a small, subterminal mouth adapted for feeding at or near the pond and river bottom. Mrigal are omnivorous scavengers, consuming detritus, decaying plant matter, small invertebrates, and organic sediment, a feeding niche that complements the surface-feeding catla and column-feeding rohu in polyculture ponds. They grow to a moderate size, generally smaller than catla, and their tolerance of varied water conditions and efficient use of pond-bottom resources make them a valuable component of South Asian aquaculture systems.

• Slender, elongated, fusiform body, less deep than catla or rohu
• Fine, small silvery scales with a bluish-grey sheen on the back
• Small, subterminal mouth positioned for bottom feeding, with short, thin barbels
• Lower fins often show a reddish or orange tinge, useful for distinguishing from rohu
• Lacks the pronounced head hump seen in large catla
• Distinguished from rohu by its more slender body and less pointed snout
• Distinguished from catla by its much smaller mouth and lack of an upturned jaw
• Overall silhouette is streamlined and torpedo-like compared to the deeper bodies of its farmed relatives

Mrigal are native to the major river systems of the Indian subcontinent, including the Ganges, Brahmaputra, and associated floodplain wetlands, and have been introduced across South and Southeast Asia for aquaculture. In rivers, they inhabit moderate to slow currents and floodplain lakes, often near the bottom where they forage over silt and organic sediment. During the monsoon, mrigal move into flooded plains and tributaries to feed and spawn in association with rising water levels. In pond aquaculture, they are stocked as the bottom-feeding component of polyculture systems, occupying substrate habitat that catla and rohu do not exploit, and tolerating moderately turbid, nutrient-rich water typical of managed ponds.

Mrigal are primarily bottom feeders and scavengers, sifting through sediment and detritus for organic matter, small invertebrates, and decaying plant material, a feeding behavior that lets them thrive on nutrients unused by surface- and column-feeding carps. They are social fish, often found in loose aggregations near the bottom of rivers, floodplain lakes, or ponds. Like other Indian major carps, mrigal undertake seasonal breeding migrations in the wild, moving to flowing water during the monsoon to spawn, with eggs and larvae drifting to nursery habitats in floodplains. In aquaculture, breeding is typically induced through hormonal stimulation since mrigal rarely spawn naturally in static ponds, reflecting their reliance on flowing water cues in the wild.