Petshrimp.com -- All about shrimp

Common Name:	Rusty Macro
Scientific Name:	Macrobrachium sp.
Size:	up to 8cm (excluding claws) for males, up to 6.5 cm for females
Temperature:	best kept at 72°F-80°F
Water Parameters:	Needs soft to medium hard, alkaline water over the long run. Should not be kept in acidic water at all.
Food:	fish food (flake, pellets etc), hair and string algae, "anything edible"
Origin:	India, possibly also neighboring countries to the east and northeast
Larval Development Type:	Completely Suppressed: Larvae assume a benthic lifestyle after hatching, i.e. they are miniature versions of the adults. There is no planktonic larval stage.

The rusty macro was another "brand new" shrimp in the American hobby and wordwide back around the middle of the last decade. Unfortunately, the species has been lost to the hobby and only new imports can reintroduce this beautiful animal to our Aquaria. Mature males have a beautiful solid rusty-brown color with dark brown to almost black claws. The males of this species are the only solid-colored Macro I am currently aware of. The females have a very nice reddish-brown interrupted stripe pattern and carry bright green eggs when gravid. Juveniles have very distinctive red bands on their chelae and brownish-red spots on their bodies. All in all this is an extremely attractive shrimp and should not be amiss in the tanks of Macrobrachium fanciers.

This shrimp should be kept in pairs in tanks with many hiding spaces as this species displays very high intraspecific aggression. A small harem consisting of one male and several females could possibly be housed in larger tanks. This species is extremely prolific. The females release 50-80 young every 40-50 days depending on temperature. In my tank my female molts right after releasing her young and becomes ovigerous immediately. As with other macros, the male displays courtship behavior towards the female to convince her to mate with him. With his chelae spread out wide, as if to hug the female, the male follows the female around the tank and chases away potential competitors (other males). It is very hard to describe this courtship, but these types of interesting behaviors make macros very appealing objects of observation.

Although very aggressive and predatory towards smaller fish (such as guppies, tetras, etc.), it could possibly be kept together with large and fast, peaceful fish such as rainbowfish. Smaller fish will be in danger of getting eaten (especially while sleeping at night) and larger aggressive fish, such as most cichlids, will eat or maim the shrimp! Hence they are best kept in their own species tank in pairs or harems.