Red ridged clinging crab (Mithraculus forceps) care guide
- Group
- Other invertebrates
- Other names
- Red-ridged clinging crab, Red clinging crab, Red emerald crab, Mithrax forceps
- Family
- Mithracidae (formerly Majidae)
- Origin
- Western Atlantic, from North Carolina through the Gulf of Mexico and Caribbean to southern Brazil, on reefs and seagrass at 0–90 m
- Water
- saltwater
- Maximum size
- 3 cm
- Temperature
- 22–27°C
- pH
- 8.1–8.4
- Hardness
- dKH 8–12, SG 1.023–1.025
- Minimum tank
- 40 litres
- Care level
- beginner
- Temperament
- semi_aggressive
- Reef safe
- with_caution
- Lifespan
- 2–3 years
Care
The red ridged clinging crab is a small, reddish relative of the emerald crab from the western Atlantic, ranging from North Carolina through the Gulf of Mexico and Caribbean to southern Brazil. It lives on reefs and in seagrass, down to about 90 m, and sometimes associates with sea anemones. It is a few centimetres across; SeaLifeBase gives no maximum size, so the size here is general guidance. Set-up: a reef tank of 40 litres or more with rock and crevices to hide in. Water figures here are general reef guidance rather than from a source. Aim for 22–27 °C, pH 8.1–8.4, dKH 8–12 and SG 1.023–1.025. Clean-up crew: like the emerald crab, it scavenges leftover food and picks at algae, including hair and bubble algae, though it is usually less effective on bubble algae. It is small and secretive, and good in nano reefs. Reef safety: mostly reef safe, but hungry crabs may pick at coral polyps or small invertebrates; feed it a little extra. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most other invertebrates. Never treat a tank holding them with copper, check the label of any fertiliser or medicine, and keep nets and buckets used for copper-treated tanks separate. Sources: SeaLifeBase (sealifebase.se/summary/Mithraculus-forceps.html). Checked October 2026.
Diet
An omnivore. It eats algae, detritus and leftover meaty food. Supplement with dried seaweed and small meaty foods.
Breeding
Sexes are separate, with a common courtship ritual and usually indirect sperm transfer; females carry eggs under the body. The larvae are planktonic, so young are not raised in home tanks, although the species has been reared in research aquaculture.
Compatibility and tank mates
Generally peaceful with fish and corals when fed, but may take polyps or small invertebrates if hungry. Do not keep with crab-eating fish such as triggers, puffers, hogfish and large wrasses.
Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.