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Little Shop of Coral

Long Spine Urchin (Diadema setosum)

Long Spine Urchin (Diadema setosum)

$40.00 CAD
$40.00 CAD
Sale Sold out
Size

The Long Spine Urchin is an excellent algae grazer with a dramatic look, featuring long, delicate spines that create instant visual impact. It spends its time cruising rockwork and glass, helping control nuisance algae in established systems. This urchin is reef safe in many setups, but it needs space, stable parameters, and careful placement of frags since it can knock items loose while climbing.

Why we love it

  • Strong algae grazer for rockwork and hard surfaces

  • Dramatic long-spine look that stands out in the tank

  • Active and interesting to watch as it moves through the reef

  • Great option for established tanks dealing with algae growth

Care and Compatibility

Care Level: Moderate
Temperament: Peaceful
Reef Safe: Yes, with caution
Diet: Herbivore
Adult Size: Body up to ~3" with long spines
Minimum Tank Size: 40 gallons recommended (larger ideal)

Ideal Parameters

  • Temperature: 24 to 26 C (75 to 79 F)

  • Salinity: 1.024 to 1.026

  • Stable alkalinity and calcium support spine health

Feeding

In most established tanks, it will graze naturally, but supplemental feeding helps if algae is limited.

  • Film algae and algae growth on rockwork

  • Dried seaweed (nori) on a clip or rubber-banded to a rock

  • Algae wafers or herbivore pellets if needed
    If the tank is very clean, it may start grazing coralline algae, so provide nori regularly.

Tank and Setup Notes

  • Secure frags and loose decor, urchins can bulldoze and dislodge items

  • Provide stable rockwork, it will climb everywhere

  • Use intake guards on powerheads and overflows when possible

  • Avoid sudden salinity swings, echinoderms are sensitive to rapid changes

  • Handle carefully, spines can be sharp and may irritate skin

Compatibility Tips

  • Generally safe with corals, but may irritate corals it crawls over

  • Can eat some macroalgae, use caution in tanks with display macros

  • Avoid predators like triggers and some puffers that may bite spines

  • Best in tanks with enough grazing surfaces and stable, established algae growth

Acclimation and Health

Drip acclimation is recommended. Avoid exposing it to air for long periods during transfer when possible. Once settled, it is typically hardy, but long-term success depends on stable parameters and consistent access to algae or supplemental feeding.

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LIGHT

LOW: Place coral at the bottom of the tank. Depending on the type, coral may need to be placed off sand and therefore mounted on a ceramic disc of piece of rock.

MEDIUM: Place coral at mid-range of the tank. Best placed/glued on top of a rock scape at mid-range height. 

HIGH: Place coral from mid range to just below water level. SPS coral are shallow growing so they require and are able to tolerate intense light.

FLOW

LOW: Most soft coral do well with a small, gentle pulse. There are certain corals that can even be placed in areas of indirect flow, meaning places aside a rock structure or set into a entrance to a cave style space.

MEDIUM: Many LPS types of coral prefer medium pulse current. Most Euphyllia or corals that have more tissue structure connected to their skeleton, don’t like to be in a high flow area like the direct flow of the wave pump.

HIGH: Similar to high light, SPS enjoy being in some heavy current. Most LPS and SPS that branch encrust or plate prefer high flow that simulates the top water waves.

SKILL

ENTRY: While some may say beginner level, "Entry" is a good term to be used when starting out in the world of corals and marine life. Prior to adding livestock, you want to ensure that your reef has the proper parameters including zero levels of ammonia and nitrite. Seeing traces of nitrate in your waters is a good sign - just keep them at a lower level of 2ppm to 10ppm. Maintaining correct temperature and salinity are a huge factor to stable parameters. Starting to monitor your PH, alkalinity, calcium and magnesium is a great habit to get into to keep a successful reef.

While some soft coral don’t require too much light, having a proper reef light that puts out the proper pars is very important. You'll also want to have a good amount of flow and protected rock areas, as placing corals in their happy spot is ideal for success.

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