Catla (Labeo catla)

Catla (Labeo catla), commonly known simply as Catla, is a large freshwater fish species native to the rivers and ponds of South Asia. It is one of the most economically significant species in Indian aquaculture, forming a key component of the Indian major carp group along with Rohu (Labeo rohita) and Mrigal (Cirrhinus mrigala). Valued for its rapid growth, high market demand, and nutritional qualities, Catla plays an essential role in inland fisheries and aquaculture throughout India, Bangladesh, Nepal, and Pakistan.

Taxonomy and Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Actinopterygii (ray-finned fishes)
• Order: Cypriniformes
• Family: Cyprinidae (carps and minnows)
• Genus: Labeo
• Species: Labeo catla

The species was first described scientifically by F. Hamilton in 1822. It is locally known by various names: “Katla” or “Katol” in Hindi and Bengali, and “Bangarutha” in Telugu.

Morphological Features

Catla is a large, deep-bodied fish with a distinctive appearance that sets it apart from other carps.
Key characteristics include:

• Body shape: Deep and laterally compressed with a curved dorsal profile.
• Head: Very large, broad, and prominent, comprising nearly one-third of the body length.
• Mouth: Wide, upturned, and terminal (facing upwards), indicating surface feeding habits.
• Scales: Cycloid (smooth-edged) and relatively large.
• Colouration: Bluish-grey dorsally, silvery on the sides, and whitish on the ventral side.
• Fins: Pectoral, pelvic, dorsal, and anal fins are greyish, while the caudal fin is deeply forked.

Adult Catla can attain a length of over 1 metre and weigh up to 45 kilograms under natural conditions, though typical aquaculture specimens range between 1 and 10 kilograms.

Distribution and Habitat

Catla is native to the Indo-Gangetic river systems of northern India, Bangladesh, and Nepal, and has been introduced widely across South and Southeast Asia.
Natural habitat:

• Large rivers, floodplain wetlands, lakes, and reservoirs.
• Prefers clear, well-oxygenated water with moderate current.
• Occupies the surface and upper column of water bodies, rarely venturing to the bottom.

Through aquaculture and stocking programmes, Catla now occurs in almost all states of India and in countries such as Myanmar, Sri Lanka, and Thailand.

Feeding Habits and Behaviour

Catla is a surface and column feeder, primarily consuming zooplankton and phytoplankton.

• In early life stages, it feeds on microscopic algae and protozoans.
• As it grows, it prefers zooplankton such as cladocerans, rotifers, and copepods.
• The upturned mouth and large gill rakers are adaptations for filter feeding near the water surface.

Catla exhibits gregarious behaviour, often forming schools with other major carps. Its feeding activity peaks during daylight hours, particularly in the early morning and late afternoon.

Reproduction and Life Cycle

Catla is a seasonal breeder, with spawning triggered by the onset of the south-west monsoon (June to August). In natural conditions, it breeds in rivers where water levels rise and currents intensify.

• Spawning grounds: Sandy or gravelly riverbeds with strong flow.
• Fecundity: A mature female may produce between 0.1 to 1.5 million eggs depending on size.
• Eggs: Semi-buoyant, non-adhesive, and hatch within 15–18 hours at optimal temperature (27–30°C).

In aquaculture, induced breeding is carried out using synthetic hormones such as Ovaprim or pituitary gland extracts. The hatchlings (spawn) are then reared in nursery ponds before being transferred to grow-out ponds.

Growth and Aquaculture Significance

Catla is renowned for its fast growth rate and compatibility with other carp species, making it ideal for polyculture systems.
Key features in aquaculture:

• Growth: Under proper management, Catla can reach 1–1.5 kg within a year.
• Culture type: Commonly reared with Rohu and Mrigal, where Catla occupies the surface niche.
• Stocking ratio: Typically 30% Catla, 40% Rohu, and 30% Mrigal in composite culture.
• Feed: In ponds, it feeds on natural plankton; supplementary feed includes oil cakes, rice bran, and formulated pellets.
• Water quality: Requires dissolved oxygen above 5 mg/L and temperature between 25–32°C for optimal growth.

Its rapid growth, market value, and adaptability make it one of the cornerstone species of Indian aquaculture, contributing significantly to inland fish production.

Economic Importance

Catla is highly prized in South Asian markets for its flavour, size, and texture. The species provides substantial economic benefits to fish farmers, traders, and rural communities.
Major uses and values:

• Food fish: Popular for its tender flesh and moderate fat content.
• Livelihood support: Provides employment in hatcheries, nurseries, and fish markets.
• Nutritional value: Rich in protein (17–20%), omega-3 fatty acids, calcium, and phosphorus.
• Export commodity: Frozen and processed Catla is exported to international markets, particularly in South and Southeast Asia.

Environmental and Ecological Role

As a surface feeder, Catla helps maintain ecological balance in aquatic systems by controlling plankton populations. It coexists well with bottom and column feeders, reducing competition for food resources.
However, the introduction of Catla beyond its native range requires ecological caution, as it may affect local fish biodiversity if stocked indiscriminately.

Diseases and Challenges

Like other aquaculture species, Catla is susceptible to several bacterial, fungal, and parasitic diseases, particularly under poor management conditions.
Common diseases include:

• Epizootic Ulcerative Syndrome (EUS) caused by fungal pathogens.
• Bacterial infections such as Aeromonas hydrophila.
• Parasitic infestations including Argulus (fish louse) and Dactylogyrus (gill fluke).

Preventive measures include maintaining water quality, avoiding overstocking, using probiotics, and ensuring regular health monitoring.

Conservation and Genetic Resources

Although Catla populations in the wild have declined in certain river systems due to overfishing, pollution, and habitat alteration, the species remains abundant in culture.

• Seed production centres across India ensure a steady supply of hatchlings.
• Genetic improvement programmes aim to enhance growth, disease resistance, and feed conversion efficiency.
• Selective breeding initiatives, such as those under the Indian Council of Agricultural Research (ICAR), are improving aquaculture productivity.

Distinguishing Features from Other Major Carps

This complementarity makes them ideal for composite carp culture, optimising the use of available food and space in ponds.

Significance

Catla (Labeo catla) embodies the success of traditional and modern aquaculture in South Asia. As one of the Indian major carps, it not only sustains rural livelihoods but also contributes significantly to food security and nutrition.