Giant river prawn

Appearance

Rosenberggarnele
© Citron / CC BY-SA 3.0, Macrobrachium rosenbergii, CC BY-SA 3.0

Until they reach sexual maturity, Rosenberg shrimps / giant river prawn are uncoloured and slightly transparent. In the males, the shear arms then begin to grow and turn orange. With increasing age, the shear arms turn blue and reach almost twice the body length.

The shear arms of the females remain shorter. They have smaller scissors with beige tips. Their belly shield is wider than that of their male conspecifics. The scissor arms of both sexes are covered with 3 mm long, pointed thorns. The body of the Giant river prawn is bluish-green translucent.

Attitude

giant river prawn are difficult to keep in an aquarium for various reasons.

Due to their size alone, adult animals are not suitable for a normal hobby aquarium. Even if the young animals in the pet shop are still small, they grow up extremely fast. The tank for one animal must be at least 1.50 m long, with a capacity of 1000 litres.

Giant river prawn are very aggressive, even within their own species. If you want to keep several animals together, the tank must be considerably larger. Alternatively, place each animal in its own tank.

Adult Giant river prawns live in Asia and the Indo-Pacific region in coastal waters.
The water in the aquarium should have a pH value of 7 to 8 and be 22 to 27 degrees warm. They prefer rather hard water.
Sand, larger stones and some robust roots are sufficient as equipment in the water tank. Plants are quickly cut off, cut up and eaten by Giant river prawn. There is also the danger that the animals get caught on the plants with the thorns on the shearing arms.

Stable hiding places made of stones are absolutely necessary. In them, individual animals can protect themselves from the attacks of others. Make sure that the caves are open in front and behind. All shrimps shed their skin. They throw off the old shell and retreat to a hiding place. There they wait until the new shell has hardened.

Food

Giant river prawn eat predominantly animal food. However, they do not spurn plant food either. Adult animals are fish predators. They not only eat carrion, but also hunt actively themselves.
Giant river prawn need protein food several times a week. Water fleas, worms and snails function as live food. Alternatively they eat frost food or freeze-dried food. A few algae, fruits, seeds and in autumn some brown leaves complete the diet.

Breeding

It is not possible to breed the Giant river prawn in the domestic aquarium.

In nature, the larvae change biotopes during their development. These biotope changes are very costly for the owner of an aquarium and therefore not practical.
If a female has freshly shed her skin, a male will place his semen package in the female’s semen container. After fertilization, the female transports about 100,000 eggs with the bristles of her swimming legs into the breeding chambers between her first and fourth pair of swimming legs.

With her swimming legs, the female shrimp constantly fans fresh water to the eggs. After 17 to 23 days the larvae hatch and are ejected by jerky movements of the abdomen.

These tiny creatures are washed into the sea (brackish water) by the current as zooplankton. If the larvae remain in fresh water, they die. In the sea, the larvae develop into small shrimps in a metamorphosis comprising eleven stages. After 16 to 35 days, the young shrimp migrate back into the rivers. Roseberg shrimp are successfully bred as edible shrimp in large facilities in Asia.

Association

You can only give Giant river prawn small, very agile fish, such as dwarf carps, to the company. All other fish quickly fall victim to the long claw arms and end up in the shrimp’s stomach.

All snails are also on the menu. This large arm shrimp is not compatible with crabs or shrimps. There are fights that often end with the death of the shrimp.
If the tank is big enough, bee shrimp and ring hand shrimp have a chance. They are fast enough to escape.