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Saltwater Aquarium Crabs

(13 items)

Crabs are a popular choice for reef tanks thanks to their utility, hardiness, and ability to help manage algae, detritus, and leftover food. From emerald crabs and hermits to eye-catching species like Pom Poms and Sally Lightfoots, they offer natural scavenging behavior while adding variety to your tank’s livestock.

At Top Shelf Aquatics, we stock a selection of saltwater crabs that are reef-safe when properly cared for and matched with the right tankmates. Each crab is housed in a stable, species-appropriate system and evaluated for health and behavior before being listed. We provide guidance on compatibility and care so you can build a reliable, balanced cleanup crew.


Whether you’re maintaining a nutrient-rich reef or just starting to stock your first tank, our selection of crabs offers practical benefits and long-term reliability.

Saltwater Aquarium Crabs for Sale

Blue Leg Hermit Crabs
Blue Leg Hermit Crabs
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Red Leg Hermit Crabs
Red Leg Hermit Crabs
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Electric Blue Hermit Crab
Electric Blue Hermit Crab
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Emerald Crab – Consumes Bubble Algae
Emerald Crab – Consumes Bubble Algae
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Price
Price
$199
$199
$1499
$799
Description
Description
Small and active, Blue Leg Hermits are excellent scavengers that clean algae, detritus, and leftover food. Reef-safe and peaceful, they’re great for nano and larger tanks with plenty of empty shells available.
A hardy cleanup crew staple, Red Leg Hermits graze on algae and leftover food while staying mostly peaceful toward tankmates. Their calm nature makes them a good addition to reef tanks of all sizes.
Strikingly colored and more assertive than other hermits, Electric Blue Hermits are excellent algae grazers but may show aggression toward smaller tankmates. Best kept in larger reef tanks with ample space and spare shells.
Best known for eating bubble algae, Emerald Crabs are reef-safe with caution. They’re efficient scavengers but may pick at coral or inverts if underfed—ideal for tanks with algae issues and good rock structure.

Dive Deeper: Info & Tips for Saltwater Aquarium Crabs

Saltwater crabs are opportunistic scavengers, feeding on detritus, leftover food, and algae. They are highly effective in controlling unwanted growths and breaking down organic matter. Hermit crabs, in particular, are known for climbing over rockwork, burrowing into sand, and occasionally swapping shells—so it’s helpful to keep a few spare shells in your tank.

While most reef crabs are peaceful, occasional aggression can occur if food or shells are limited. To minimize risk, avoid overcrowding and provide enough territory for each crab. They prefer stable systems with low nitrates and good oxygenation, and they can be vulnerable to copper-based treatments.

Saltwater aquarium crabs are hardworking, reef-safe inverts that play a key role in maintaining a clean and balanced marine environment. From hermit crabs that sift sand and scavenge detritus to emerald crabs that help control bubble algae, these invertebrates are a smart addition to any clean-up crew. Their small size, low maintenance needs, and diverse appearances make them ideal for reef tanks and fish-only systems alike.

At Top Shelf Aquatics, we offer a curated selection of saltwater crabs for aquariums, including popular species like blue legged and red legged hermit crabs. These inverts are peaceful, efficient, and compatible with most marine setups, helping reduce algae buildup, consume waste, and stir substrate.

Top Saltwater Crabs for Aquariums

Blue Legged Hermit Crabs – Small, active, and efficient at algae control. Ideal for nano tanks and tight crevices in reef rock.

Red Legged Hermit Crabs – Slightly larger and more robust than their blue-legged cousins. Great for sand stirring and scavenging.

Emerald Crabs – Known for their role in bubble algae control. Best kept in tanks with sufficient algae or supplemental feeding.

Scarlet Hermit Crabs – Brightly colored and peaceful. Tend to stay on the rockwork and are less aggressive than other hermits.

Porcelain Crabs – Filter feeders with unique fan-like appendages. Best for peaceful reef setups with low flow zones.

Ideal Parameter Range

  • Salinity: 1.023–1.026
  • Temperature: 74–78°F
  • pH: 8.1–8.4
  • Ammonia/Nitrite: 0 ppm
  • Nitrate: <15 ppm
  • Calcium: 400–450 ppm
  • Alkalinity: 8–12 dKH

Setting Up an Aquarium for Saltwater Crabs

Saltwater crabs thrive in well-established tanks with stable parameters and minimal aggression from tankmates. Provide ample live rock, nooks, and sandy areas for them to explore. If keeping hermits, offer empty shells of various sizes to reduce shell-fighting behavior.

Avoid housing crabs with predatory fish or other large inverts that may pose a threat. Crabs may climb overflow grates or move frags, so secure loose items and consider fine mesh in overflow areas.

Feeding Saltwater Aquarium Crabs

Most crabs will scavenge naturally in a mature system, but supplemental feeding ensures consistent health. Offer small bits of frozen food, algae wafers, or dried seaweed. Emerald crabs in particular benefit from targeted algae feedings if natural sources are low.

Avoid overfeeding, which can lead to nutrient spikes. Feed every other day or as needed, based on crab activity and tank cleanliness.

Why Buy Saltwater Crabs from Top Shelf Aquatics?

Our saltwater crabs are hand-selected, acclimated, and inspected to ensure they're healthy and ready to contribute to your tank's ecosystem. Whether you're building a cleanup crew or adding visual diversity to your reef, we provide reliable inverts that make a difference.

Each species is evaluated for compatibility, behavior, and utility to help you make the best choice for your marine system.

Saltwater Aquarium Crabs FAQs

Are saltwater crabs reef safe?

Not all crabs are automatically reef-safe. While popular species like emerald crabs and most small hermit crabs are considered safe for reef tanks, their behavior can still change depending on diet, tank space, and available resources. If underfed or lacking shells, some crabs may pick at corals or snails.

We only offer species that are reef-compatible when properly cared for, and we recommend monitoring behavior after introduction—especially in mixed tanks with sensitive livestock.

Do crabs need extra shells?

Hermit crabs rely on empty snail shells for protection. As they grow, they’ll seek out larger shells and may fight if there aren’t enough options available. Providing a variety of clean, appropriately sized spare shells helps prevent aggression and supports their natural behavior.

We recommend placing several extras in your tank if you're keeping more than one hermit crab.

Which crabs are best for algae control?

Emerald crabs (Mithraculus spp.) are excellent algae grazers, especially for bubble algae, film algae, and leftover detritus. Some hermits also assist with algae control by picking at hair algae and biofilm across rock surfaces and sand beds.

Just be aware that crabs should be seen as part of a broader cleanup crew strategy—best used alongside snails and proper nutrient management.

How many crabs should I add to my tank?

Depends on tank size and bioload. A mix of hermits and emerald crabs works well in most reef systems.

Will crabs bother my fish, snails, or corals?

Most crabs we offer are peaceful and compatible with fish, corals, and other inverts under the right conditions. However, issues can arise if food is scarce, tank space is limited, or shells are in short supply.

Always provide enough hiding spots and supplemental food if your tank is especially clean. And as with any addition, keep an eye on interactions during the first few days to make sure everything settles in smoothly.