Rock Prawn

Macrobrachium lar

Also known as Lar Prawn, Lar River Shrimp

Animalia›Arthropoda›Malacostraca›Decapoda›Palaemonidae

Macrobrachium lar, commonly called Rock Prawns, are large freshwater macrobrachium shrimp native to Southeast Asia. They display a translucent to tan body coloration with distinctive long, slender claws and antennae that can exceed their body length. These robust prawns are highly aggressive and territorial, making them unsuitable for community tanks but fascinating for dedicated species-specific setups.

At a glance

Size: 3.5 in; 9 cm
Min tank: 20 gal; 76 L
Temp: 72–82°F; 22–28°C
pH: 6.5-8.0
GH: 143–268 ppm; 8–15 dGH
Temperament: Aggressive
Swims: Bottom
Lifespan: 3-5 yrs

Ammonia 0 ppm and nitrate under 20 ppm.

Care

Diet

Rock Prawns are opportunistic omnivores that consume algae, biofilm, detritus, and small invertebrates. Supplement with sinking pellets, blanched vegetables (zucchini, spinach), and occasional protein sources like bloodworms or small crustaceans. Feed sparingly 2-3 times weekly; overfeeding degrades water quality.

Behavior

Macrobrachium lar are highly aggressive and territorial, establishing dominance hierarchons through claw displays and combat. They are primarily nocturnal, spending daylight hours hidden in caves or dense vegetation. Males are particularly combative and will injure or kill conspecifics; solitary housing is strongly recommended.

Breeding

Rock Prawns require brackish water (specific gravity 1.005-1.010) for successful larval development, making home breeding extremely difficult in freshwater. Females produce large clutches of eggs but larvae are planktonic and require marine rearing conditions. Commercial availability is limited; wild-caught specimens are more common than captive-bred.

Tank mates

See all 5

Otocinclus

May be predated upon or harassed; only in heavily planted tanks with multiple hiding spots

caution

Amano Shrimp

Risk of predation or aggression; only if tank is very large with abundant cover

caution

Java Moss

Provides essential hiding places and reduces aggression through visual barriers

good

Anubias Nana

Hardy plant that withstands shrimp activity and provides shelter

good

Bucephalandra

Durable plant offering cover without being uprooted by aggressive behavior

good

No state or federal restrictions on record.

Not legal advice, and possibly incomplete or out of date. Rules vary by state and change over time; check with your state wildlife or agriculture agency before buying, keeping or shipping it.

The care information here is written with AI help, so it can contain mistakes. Spot one? Tell us and we'll fix it.