Arrow Crab (Stenorhynchus lanceolatus) – Complete Care Guide

General Information

The Arrow Crab (Stenorhynchus lanceolatus) is a fascinating and visually striking marine invertebrate, easily recognized by its long, spindly legs and triangular body adorned with red stripes. Native to the Atlantic African coast, including regions from Cape Verde to the Canary Islands, this crab is a popular choice for marine aquarists due to its unique appearance and intriguing behavior.

Arrow Crabs play an important role in the hobby as both a decorative addition to reef tanks and a functional species that helps control certain pests, such as bristle worms. Their long legs and slender body make them agile climbers, often seen perched on live rock or coral structures. While they are not particularly aggressive, their curious nature and territorial tendencies can make them a source of entertainment in the aquarium.

Care

Arrow Crabs are relatively hardy and adaptable, making them suitable for intermediate-level aquarists. They thrive in well-established aquariums with stable water parameters and plenty of live rock for hiding and climbing. These crabs are nocturnal by nature, so providing shaded areas or caves in the tank will help them feel secure during the day.

While they are generally reef-safe, caution is advised as they may occasionally nip at soft corals or small invertebrates if underfed. Keeping them well-fed and providing a spacious tank can help mitigate such behavior.

Diet and Feeding

In the wild, Arrow Crabs are opportunistic feeders, consuming a variety of small invertebrates, detritus, and algae. In captivity, they readily accept a diet of meaty foods such as brine shrimp, mysis shrimp, and finely chopped seafood. Supplementing their diet with algae wafers or vegetable matter can provide additional nutrients.

Feed them every other day, offering only as much as they can consume within a few minutes. Overfeeding can lead to water quality issues, so monitor their intake and adjust portions as needed.

Behavior and Compatibility

Arrow Crabs are semi-aggressive and can exhibit territorial behavior, particularly towards other crustaceans or similarly sized tank mates. They are best kept singly or in large tanks where territories can be established without conflict. Avoid housing them with small, slow-moving fish or delicate invertebrates that may become targets of their curiosity.

Despite their occasional territorial tendencies, Arrow Crabs are generally peaceful towards larger, fast-moving fish and make excellent additions to community reef tanks. Their unique appearance and active behavior make them a focal point in any aquarium.

Arrow Crabs can help maintain a balanced ecosystem in the tank by preying on pests like bristle worms. This functional role adds to their appeal for aquarists looking to manage pest populations naturally.

Health and Common Issues

Arrow Crabs are hardy but can be sensitive to sudden changes in water parameters. Maintaining stable salinity, temperature, and pH levels is crucial for their health. They are also prone to stress during molting, a process during which they shed their exoskeleton to grow. Providing plenty of hiding spots will help them feel secure during this vulnerable time.

When selecting an Arrow Crab, look for individuals with intact legs and vibrant coloration. Avoid crabs with missing appendages or signs of lethargy, as these may indicate poor health.

Habitat

In their natural habitat, Arrow Crabs are found in shallow, rocky reefs and coral environments along the Atlantic African coast. They prefer areas with plenty of crevices and overhangs where they can hide and forage. Replicating this environment in the aquarium with live rock and moderate water flow will help them feel at home.

Common name: Arrow Crab