Monkey River Shrimp

The monkey river shrimp is a very large freshwater prawn of the Indo-West Pacific, known by its dark red-violet colour and extremely long pincer legs, and its young have to travel down to the sea and back.

It lives in permanently flowing creeks and rivers, often near sea level, though it can climb into upland headwaters. Deep, shaded pools and sheltered stretches of stream are where it prefers to settle. The range runs from East Africa across India and South East Asia to the Marquesas Islands.

Appearance

This is among the biggest of the freshwater prawns. The colouring is a dark red-violet, and the second pair of legs is the feature to look for: extremely long, and ending in drawn-out pincers. Males grow larger than females.

Feeding

It is not a fussy eater, taking algae, plant matter, fish and snails as the chance comes along.

Life cycle

Its life is a journey between river and sea. A female can lay as many as 8,000 eggs, and the newly hatched larvae are carried downstream to the ocean, where they grow up in salty water. As post-larvae they head back into fresh water to live out their adult lives.

Threats

It is valued as a delicacy and is taken for food by local fishers on Pacific islands such as Fiji.

Relationship with people

Fast growth and large size make it a prime candidate for farming, in the hope of matching the worldwide success of a close relative, the giant freshwater prawn (Macrobrachium rosenbergii). It is also easy to move, since it can survive for several hours out of water without being put straight on ice.

Full-scale farming still faces problems, though. Adults are strong climbers and easily get out of ponds, and the 13 larval stages mean few survive in captivity. Recent progress with greenwater rearing is helping to push domestication forward.