Purple Pincushion Urchin (Salmacis sp.)

The Purple Pincushion Urchin (Salmacis sp.) is a living algae mower dressed in purple-banded spines. It spends all day and night methodically grazing film algae, hair algae, and leftover nuisance growth off rock and glass, and it is completely peaceful toward everything else in the tank. Browse the rest of our saltwater livestock while you are here.

Care Guide

Urchins are easy keepers in an established tank with one honest requirement: enough algae to eat. Starve one and it will slowly waste; feed it and it is nearly indestructible.

• Tank size: 20 gallons or larger, established for at least a few months so there is real algae growth to graze.
• Food: Film and hair algae first. When the tank gets too clean, supplement with dried seaweed sheets clipped or rubber-banded to the rock a few times a week.
• Water: 72 to 78°F, salinity 1.023 to 1.025. Like all echinoderms it has no tolerance for swings, so acclimate slowly (a drip acclimation is ideal) and keep salinity stable.
• Aquascape: Secure your rockwork and glue down frags. Pincushions are gentle but determined bulldozers, and they love to pick up loose frags, snail shells, and rubble to wear as hats.
• Handling: The short spines are not venomous, but lift it gently and never pull it off the glass; let it release on its own.

Specifications

Compatibility

Safe with every reef fish, coral, shrimp, and snail; it competes only with other algae grazers for food, so stock one urchin per 20 to 30 gallons of algae-growing surface. Keep it away from predators of invertebrates like large wrasses, puffers, and triggers. It plays especially well alongside a cleanup crew of snails and a Strawberry Conch working the sand while the urchin works the rocks.

Recommended Foods & Supplies

• Rod's Food Leafy Purple Seaweed for supplement feeding when the rocks run clean
• Red Pom Pom Gracilaria, live macroalgae it will happily graze
• Strawberry Conch to cover the sandbed side of the cleanup crew
• Browse all saltwater livestock and supplies

FAQ

Is it reef safe?
Yes, with one asterisk: it does not eat coral, but it will pick up and carry off anything loose, frags included. Glue your frags down and it is a model citizen.

Why is it wearing my frag plug as a hat?
Decorating is normal urchin behavior, it uses cover as camouflage and sun protection. Take it as a compliment, then glue things down better.

Will it run out of food?
In a very clean tank, yes. If you see the rocks looking spotless, clip in a piece of dried seaweed a few times a week and it will stay fat and healthy.

Are the spines dangerous?
No. This is a short-spined, non-venomous species. Handle it gently and let it release its grip on its own rather than pulling.