Livestock | Marine | Marine Inverts and Snails | Urchins

Keeping Urchins in Marine Aquariums

Urchins are fascinating echinoderms that bring both function and visual intrigue to marine aquariums. With their slow movements, spiny forms, and algae-grazing behavior, they serve as valuable cleanup crew members while adding diversity and texture to reef tanks.

General Care Tips:
Urchins thrive in stable, mature aquariums with temperatures between 72–81°F and a pH of 8.1–8.4. Good water quality, ample live rock, and a healthy supply of algae are essential for long-term success. They require strong surfaces to graze on and often move along the rockwork, glass, and substrate in search of food.

Feeding:
Most urchins are herbivores or omnivores that graze on various types of algae, including film algae, coralline algae, and hair algae. Some, like the pincushion and tuxedo urchins, are excellent for controlling nuisance algae. In algae-poor tanks, supplement their diet with dried seaweed (nori) or algae wafers to ensure proper nutrition.

Compatibility and Behavior:
Urchins are generally peaceful and reef safe, though larger or more powerful species may knock over loose corals or rockwork while grazing. Some species are considered reef safe with caution due to their potential to graze on coralline algae or soft coral tissue when underfed. Urchins are best housed in systems with secure rock structures and minimal aggressive tankmates, as their slow movement makes them vulnerable.

Popular Urchin Species:

• Tuxedo Urchin (Mespilia globulus): Compact and reef safe, known for carrying shells or debris on its back.

• Blue and Red Tuxedo Urchins: Colorful, peaceful algae grazers ideal for community reef tanks.

• Longspine Urchin (Diadema setosum): Excellent algae eater but grows large and has sharp, venomous spines—reef safe with caution.

• Pincushion Urchins (Lytechinus spp.): Hardy and active algae grazers, best for medium to large tanks.

• Rock Boring Urchins (Echinometra mathaei): Small and tough; good for algae control in smaller systems.

• Pencil Urchins (Eucidaris and Heterocentrotus spp.): Hardy but not fully reef safe—may graze corals or other invertebrates.

• Armadillo Urchins (Colobocentrotus spp.): Unusual, flattened appearance and hardy; suitable for display tanks with firm footing.

Special Considerations:
Urchins require stable calcium and alkalinity levels for healthy spine growth, much like corals and snails. They are sensitive to copper and other medications, so only treat the tank with reef-safe additives. Some urchins may lose spines due to stress, poor water quality, or aggression, which is often reversible if conditions improve.

Summary:
Urchins are hardy, helpful, and captivating additions to marine aquariums. With their algae-eating habits, peaceful temperament, and unique appearance, they contribute to both the health and beauty of a reef tank. Ideal for intermediate to advanced aquarists, urchins reward proper care with long life and excellent utility in algae management.