Breeding the Red Mithrax Crab (Mithraculus forceps)
Mithraculus forceps is a small Caribbean clinging crab whose egg-carrying females release planktonic zoea larvae. Lab studies have reared it through two zoeal stages and a megalopa, but it is not home-bred.
Overview
Mithraculus forceps (A. Milne-Edwards, 1875), the red mithrax or red clinging crab, is a small western-Atlantic spider crab resembling a compact emerald crab. It eats algae and detritus and suits nano reefs. It is one of the marine ornamental crabs studied as a candidate for aquaculture because of its short larval cycle.
Sexing
As with other true crabs, sex is read from the abdominal flap: males show a narrow abdomen, females a wide rounded one used to brood eggs. A female carrying a clutch beneath her abdomen is termed ovigerous and signals an imminent larval release.
Spawning & Larvae
The female broods fertilized eggs under her abdomen until hatching. Larval development comprises two zoeal stages and one megalopa. In rearing trials, best survivorship and fastest development came at about 28 °C with larvae fed newly hatched Artemia nauplii, reaching roughly 74% survival to 12 days post-hatch; starved larvae failed to reach zoea 2.
Common Challenges
- Planktonic zoeae are removed by skimmers, filters and pumps in a closed system.
- Larvae require a constant supply of live planktonic food and die quickly if unfed.
- Rearing needs separate larval and megalopa tanks with tight temperature and salinity control.
- Megalopae can show aggressive interactions when crowded, complicating rearing.