Natural Habitat:Indo-Pacific, Atlantic
Tank Requirements:Provide caves and rockwork; supplements of calcium and iodine are beneficial for aiding molting process.
Behavior:Most species are nocturnal; scavenger; predatory; spends daylight hours in dimly lit areas; may harm small fish and invertebrates; produces loud snapping sounds
Compatibility:Most are Community Safe and Reef Safe with caution; avoid keeping with other shrimp, very small tankmates or large predators
Feeding:Opportunistic scavenger; meaty foods
BehaviorPistol Shrimp are interesting and unique additions to saltwater aquariums. They were once considered nuisance creatures and were only found as unwanted hitchhikers in pieces of live rock or coral. Now, many species are highly sought after as tank additions in their own right and their fascinating behavior has become the stuff of internet lore.
The name "Pistol Shrimp" comes from one of their claws which has become adapted over time. This claw is larger than the other and has a groove in its structure. When the pistol shrimp is threatened, it opens this claw and prepares it much like a gun is cocked. When the claw snaps shut, this groove channels water and forces it out at speeds that can approach sixty miles per hour. This produces a bubble from the pressure changes and when this bubble collapses, the snapping sound it produces is one of the loudest sounds in the ocean - loud enough to even appear on submarine sonar around colonies of pistol shrimp! The bubble's collapse is even powerful enough to produce intense heat and even light in that instant and location. This snapping is uses to scare off potential predators and even kill small fish, shrimp or other creatures who are hit by the impact.
CompatibilityDespite this rather fearsome defense, most pistol shrimp are safe in community and reef aquariums. This "shooting" isn't usually used to hunt and, while you may hear snapping coming from your aquarium, the pistol shrimp don't usually attack any tankmates that leave them alone. Some pistol shrimp even form a relationship with some other fish like the aptly-named Shrimpgobies or with corals, anemones and other organisms. Not all pistol shrimp form these pairs however; research your choices carefully.
Compatible tankmates for pistol shrimp can vary depending on the species. Most can be kept with any non-shrimp-eating tankmates but should not be kept with other shrimp or with very small rock-dwelling fish like Clown Gobies and some blennies. Some pistol shrimp form elaborate burrows in the substrate so all rockwork must be kept very stable to prevent it from collapsing. Pistol shrimp are generally scavengers and will feed on small meaty foods and detritus. Since most pistol shrimp rarely stray far from their homes, you may need to target-feed your shrimp with foods like brine shrimp, mysis shrimp, scallop and similar foods to make sure they are not outcompeted for food by their tankmates.
Like other crustaceans, pistol shrimp have to molt their hard exoskeleton to grow. Mineral and iodine supplements are helpful in forming a hard, healthy skeleton. The levels found in quality salt mixes are usually enough but in heavily-stock reef tanks, extra supplements may be needed. Also, regular water changes to replenish the minerals and keep the water quality pristine are also necessary. While some species of pistol shrimp can grow to a few inches in length, most stay very small and can be kept in small nano-tanks.