Kaira River Prawn (Macrobrachium dayanum) — 2-4cm

Overview

The freshwater shrimp Macrobrachium dayanum, commonly known as the kaira river prawn, is a compact South Asian species with interesting behaviour and semi-aggressive nature, making it ideal for species tanks or carefully planned community setups. Native to river systems of India and surrounding regions, this distinctive freshwater prawn displays robust build, active scavenging behaviour, and specialized care requirements that make it a rewarding addition for experienced aquarists. Available for sale UK hobbyists seeking unusual freshwater invertebrates should note that this species requires moderate-level care with semi-aggressive temperament and potential predatory tendencies towards smaller tankmates. At 2-4cm, these specimens are juveniles that will reach adult size of approximately 4cm.

Appearance and Colouration

Macrobrachium dayanum displays subtle colouration ranging from translucent grey to light brown or olive-green, often with faint banding or mottling along the body and rostrum. The rostrum is long and serrated, characteristic of the Macrobrachium genus, and the claws are moderately sized and used for feeding and defence. At 2-4cm, juveniles are already recognisable and will develop more intense colouration and larger claws as they mature. The eyes are prominent on stalks, providing excellent vision for nocturnal foraging. Colouration can vary depending on diet, substrate, and stress levels, with well-fed, secure specimens displaying the most vibrant tones.

Natural Habitat

Native to river systems across South Asia, especially India, Macrobrachium dayanum inhabits clear to moderately turbid waters with rocky or sandy substrates, submerged wood, and abundant hiding places. These environments feature warm, well-oxygenated water with moderate flow and complex structure. In the wild, kaira river prawns are opportunistic omnivores and scavengers, foraging for detritus, biofilm, small invertebrates, and plant matter. They are adapted to navigate murky waters using their highly sensitive antennae and are most active during twilight and night. Recreating these conditions with hiding places, moderate flow, and stable water chemistry supports natural behaviour and reduces stress.

Aquarium Setup

Provide a minimum of 60 litres with efficient filtration and stable water parameters. Use a fine sand or smooth gravel substrate and furnish the aquarium with driftwood, rocks, caves, live plants such as Java moss and Java fern, and hiding places to provide security. Maintain moderate water flow and excellent oxygenation. Install a secure, tight-fitting lid, as prawns are capable climbers and may escape. Perform regular partial water changes to maintain pristine water quality. Provide abundant plant cover and leaf litter to encourage natural foraging behaviour and offer safe moulting sites. A mature, biologically stable aquarium is ideal for this species.

Diet and Feeding

Macrobrachium dayanum is an omnivorous scavenger that accepts a wide variety of foods. Offer sinking carnivore pellets, algae wafers, blanched vegetables such as spinach and courgette, frozen or live foods such as bloodworms, daphnia, brine shrimp, and occasional protein-rich foods such as small pieces of raw shrimp or fish. Provide calcium-rich foods such as cuttlebone or specialised invertebrate supplements to support healthy moulting. Feed in the evening when the prawn is most active, and remove uneaten food after a few hours to maintain water quality. A varied, balanced diet promotes vibrant health, successful moulting, and natural behaviour.

Behaviour and Temperament

Kaira river prawns are semi-aggressive and exhibit opportunistic predatory behaviour, particularly at night when they are most active. They spend daylight hours hidden in caves or under décor, emerging after dark to forage and hunt. This species is territorial and may defend chosen hiding places from other prawns or tankmates. During moulting, the prawn will seek shelter and remain hidden until the new exoskeleton hardens, a vulnerable period lasting several days. Observe carefully if housed with fish, as this species can catch small or slow tankmates at night. It is best suited to species-only setups or housing with robust, fast-swimming fish.

Suitable Tank Mates

Compatible with fast, peaceful fish that are too large to be preyed upon, such as larger barbs, rainbowfish, and robust tetras. Snails may be tolerated, though small specimens could be vulnerable. Avoid small fish fry, shrimplets, tiny fish, slow or long-finned fish, and other prawns or shrimp in cramped tanks. Choose tankmates that are robust, agile, and occupy different areas of the aquarium. Best kept in a species-only setup or with very carefully selected companions. Careful observation is essential if housing with fish, and be prepared to separate if predation occurs.

Breeding

Breeding in captivity is uncommon. Like many Macrobrachium species, reproduction may involve larval stages that are difficult to raise and may require specific water conditions including possible brackish salinity for larval development. If breeding is attempted, provide excellent water quality, stable parameters, and abundant hiding places for egg-bearing females. Larvae are planktonic and require specialised care with microscopic live foods and appropriate salinity management. Most aquarists keep Macrobrachium dayanum for display rather than breeding, though dedicated enthusiasts with appropriate equipment and experience may achieve success with careful research and preparation.

Special Considerations

Provide plenty of hiding places, driftwood, rocks, and dense cover, especially during moulting when the prawn is vulnerable. This species can be predatory toward smaller tankmates and may become more aggressive when hungry or defending territory. Avoid all copper-based medications, which are highly toxic to crustaceans. Maintain stable water chemistry and provide adequate calcium to support healthy moulting and exoskeleton development. After moulting, leave the shed exoskeleton in the tank for the prawn to consume as a calcium source. Monitor tankmates closely, especially at night, and be prepared to separate if predation occurs. Best suited to experienced aquarists comfortable managing semi-aggressive, predatory invertebrates.

Why Buy from Tropical Fish Co

Tropical Fish Co is a trusted UK supplier of healthy, active freshwater prawns including Macrobrachium dayanum. Each specimen is carefully selected for robust health, active behaviour, and excellent condition. Our livestock is quarantined and health-checked before dispatch, ensuring you receive only the finest quality. We provide expert care advice, detailed species information, and ongoing support to help you succeed with your prawns. With fast, secure delivery across the UK and a commitment to sustainable fishkeeping practices, Tropical Fish Co is your reliable partner for premium freshwater invertebrates and aquatic livestock.