Arrow Crab
Stenorhynchus seticornis
Saltwater Invertebrate
Species Group: Crab
Family: Majidae
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Water parameters
Temp
76-80 F
Temperature
Maintaining a stable and appropriate temperature is critical for the survival of aquatic life.
pH 7.8 - 8.4 potential of HydrogenMeasuring the acidity or alkalinity of water on a 0–14 scale, where 7 is neutral, 7 is alkaline.
NO3 1-20 ppm NitrateWhile less toxic than ammonia, high nitrate levels (above 40–80 ppm) are important to monitor because they can cause fish stress, stunted growth, and harmful algae blooms.
NO2 <0.0001 ppm NitriteIt is a highly toxic, intermediate compound in the nitrogen cycle produced from broken-down ammonia
PO4 0.01 - 0.1 ppm PhosphateIt is essential for plant development but must be managed, as excess levels trigger nuisance algae blooms and inhibit coral calcification.
NH3 <0.1 ppm AmmoniaIt is the primary killer of aquarium fish, causing gill damage, stress, and death
Ca 380 - 450 ppm CalciumSupporting the growth, skeletal structure, and shell formation of corals, mollusks, crustaceans, and coralline algae
KH 8 - 12 dKH AlkalinityIt acts as a shield, neutralizing acids to prevent dangerous pH "crashes" that can harm fish, corals, and plants.
Mg 1200 - 1400 ppm MagnesiumIt enables coral growth by supporting skeletal formation, assists in metabolic processes, and ensures that calcium is available for corals, clams, and coralline algae.
SG 1.023 - 1.026 SG SalinityEssential for maintaining stable, natural water parameters, proper osmoregulation, and stress-free environments for marine fish and corals
ORP 250 - 400 mV Oxidation-Reduction PotentialA higher positive mV indicates clean, oxygen-rich water with high water quality, while low readings indicate high pollution.
About Arrow Crab
General information
The Arrow Crab has extremely long legs. It is called the Arrow Crab because of the shape of the body and head. The size is variable, many reaching six inches, and some up to 10 inches. Females may be dramatically smaller. Different species inhabit different parts of the world. They normally inhabit portions of the reef usually associated with a small cave or crevice. It is a hardy, long-lived invertebrate, that can be housed in the reef aquarium. This crab has been known to attack crustaceans such as Banded Coral Shrimp, and may even attack small slow moving fish.
Diet & nutrition
Arrow Crab is a nocturnal scavenger. Its diet mainly consists of small feather duster worms and small animals found in coral reefs. It also feeds on slow-moving fish and bristles worms. They are considered safe when inside an aquarium, but they must be adequately fed with meat and pellet food. It is commonly placed in an aquarium to control the growth of bristle worms.
Determining sex
Arrow crabs are hard to sex, but males are generally larger than females.
Breeding & spawning
A male arrow crab holds the female crab against his belly and deposits a sperm packet. The female then carries the eggs until they are full grown and are ready to be hatched. Breeding inside the aquarium is usually unsuccessful. This may be because these crabs prefer to breed naturally than intentionally.
Origination
The arrow crab is native from the coral reefs of the Atlantic Ocean, from North Carolina and Bermuda up to Brazil and Caribbean. It is also common in the reefs of Florida and Texas. It can be found between the depths of 10 and 30 feet.
Cautions
Arrow crab is territorial so no other crab species can be placed in the aquarium when it is present. However, it can live harmoniously with the sea anemone (Lebrunia danae), Pederson's cleaning shrimp (Ancylomenes pedersoni) and spotted cleaner shrimp (Periclimenes yucatanicus).
Acclimation process
When taking the invertebrate out, expose it to as little light as possible and turn the aquarium lights off. Place the invertebrate container bag in the aquarium and let it float for 15 minutes. Open the bag and pour in 1 ounce of aquarium water into it, do so every 5 minutes until the water inside the bag has doubled. Wait for 5 minutes before pouring off half the water inside the bag into the aquarium. Then, slowly place each animal in the aquarium. Turn the aquarium lights on after an hour or more.
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