Updated August 6, 2019
Author: Mike - FishLore Admin
The pencil urchin is often picked up by hobbyists that want to add them to their clean up crew. This urchin will graze on algae, sponges, tunicates and does a decent job. However, they may also eat calcareous coralline algae and macro algae as well. The pencil urchin will eat meaty foods too and some hobbyists have reported that they have caught them munching on ornamental shrimps and crabs. You can usually find them online for $10 to $20 a piece and they are often on the small side but they can get up to around 6 inches (15 cm) when fully grown.
They may knock over loose frags so keep that in mind if you put one in your reef tank. They will also eat the items mentioned above so you may want to take a pass on this invert if you have a reef tank. A fish-only type tank setup of 30 gallons or more with lots of live rock for them to graze on is decent to start with. They are mostly nocturnal so you may not see them out and about when the lights are on.
Pencil Urchin Care
Scientific Name : Eucidaris tribuloides
Common Names : Mine Urchin, Primitive Sea Urchin
Care Level : Easy
Life span : several years
Size : 6 inches (15 cm)
pH : 8 - 8.4
Temperature : 72°F - 80°F (22°C - 27°C)
Specific Gravity : 1.020 - 1.026
Origin / Habitat : Caribbean
Reef Safe? : Not considered reef tank safe
Temperament / Behavior : Peaceful algae grazer
Breeding : Sorry, don't have info on breeding them at this time.
Aquarium Size : 30 gallon plus recommended
Tank Mates : They should be able to take care of themselves and most fish species will leave them alone, except for triggerfish. Triggers have been known to be able to flip them over to get at their softer undersides.
Diet / Foods : They will graze on algae (including calcerous algae), macro algae. May eat sponges and tunicates as well. Clams and mussels on the half-shell and other meaty marine origin foods will be accepted as well.
Tank Region : All over the live rock
Gender : There are no definite ways to distinguish males from females.
Similar Species : Marine Invertebrates
More Saltwater Invertebrate Profiles
Tiger Striped Brittle Star
The Brittle Stars are generally pretty good tank mates in saltwater aquariums, including reef tanks. They should just scavenge the sand and rock while leaving the fish, corals and other invertebrates alone.
Chocolate Chip Starfish
This starfish will eat other invertebrates in the tank, including soft corals such as xenia. Would only do well in fish only type tanks with no invertebrates.
Coral Banded Shrimp
Best to keep only one per tank as they may fight other coral banded shrimps. They may also go after other shrimp species, although we've kept them in tanks with other saltwater shrimp species and have had no problems.