Peacock Mantis Shrimp

With its bright green body, orange-red legs, spotted carapace and large eyes on stalks, the peacock mantis shrimp is one of the most colorful crustaceans on the reef. Although its name includes "shrimp," it is not closely related to true shrimp; it belongs to a separate order of crustaceans (Stomatopoda). The tips of its front legs are thickened like clubs, and it shoots them forward at extraordinary speed to smash the shells of snails, crabs and mussels. Its eyes can detect polarized light, which the human eye cannot see, and a large number of color shades.

This power has serious consequences in the aquarium: it hunts fish, shrimp, crabs and snails that fit in its mouth. Glass warning: the strike of large individuals can crack thin aquarium glass; the risk increases especially when it is provoked from behind the glass or when food is held close to the glass. It should not be handled; it can seriously injure a finger. Specimens in the trade are wild-collected. The small mantis shrimp that hitchhike into reef aquariums on live rock are usually other species.

It lives on sand and coral rubble bottoms around reefs from East Africa to the Western Pacific islands. It sits in U-shaped burrows it digs itself, watches for prey from the burrow entrance and comes out during the day to hunt.

• Volume: a species aquarium of at least 100 liters dedicated to it alone.
• Glass and lid: the front glass should be thick (at least 8 mm), or an acrylic aquarium should be preferred; acrylic does not crack but can be scratched.
• Substrate: 8–10 cm of mixed-grain sand, coral rubble and rocks. Rocks should be set directly on the bottom before the sand is added so that they do not collapse when it digs. A PVC pipe buried in the sand makes a ready-made burrow.
• Water: salinity 1.023–1.026 specific gravity, pH 8.1–8.4, temperature 24–27°C.
• Reef compatibility: Not reef-safe; although it leaves corals alone, it hunts all mobile invertebrates and small fish and constantly rearranges the aquascape.

Carnivorous. It feeds on shell-on shrimp, mussels and oysters, krill, chopped fish and frozen seafood; cracking open shelled foods lets it behave naturally. Feed it 3–4 times a week with long tweezers, away from the glass. Leftover shells and scraps should be removed so they do not foul the water.

A curious, intelligent hunter; it recognizes its keeper and constantly rearranges the stones and rubble in the aquarium. It claims its burrow and treats every approaching animal as a threat.

Good companions: it should be kept alone.

Avoid: all fish, shrimp, crabs, snails and mussels; a second mantis shrimp.

Kept singly. In the wild, pairs may form during the breeding season, but when two individuals are put together in the aquarium, deadly fights are common.

In the wild the male and female form a short-term pairing; the female guards the egg mass in her burrow, holding it with her front legs. The larvae develop in the plankton; breeding it in a home aquarium is not practical.

• Molting: it hides and stops eating for a period of a few days; this is normal and it should not be disturbed.
• Shell problems: insufficient calcium and a monotonous diet can make molting difficult; food should be varied.
• Medication: copper-based medications are lethal.

Males have thin, rod-shaped reproductive appendages at the base of their last walking legs; females lack these appendages. Telling them apart externally takes experience.