Beyond the Fish: The Most Charming Little Creatures for a Marine Tank

In this guide

Tags: marine invertebrates, hermit crabs, cleaner shrimp, reef tank cleanup crew, saltwater snails

Fish get most of the attention in a marine tank, but some of the most entertaining residents have no fins at all. Marine invertebrates, the shrimp, crabs, snails, and starfish that share the tank, bring their own personalities, and several of them are genuinely endearing to watch once you know what to look for.

Shrimp with real character

• Cleaner shrimp, which set up a cleaning station and pick parasites off willing fish, an interaction that never quite loses its charm
• Peppermint shrimp, small, active, and useful for controlling pest anemones
• Fire shrimp, a bright red species that adds a splash of colour to rockwork
• Pistol shrimp, which dig burrows and often pair up with a watchman goby in one of the more delightful partnerships in the reef world

Crabs worth getting to know

• Blue leg hermit crabs, tiny and constantly busy grazing on algae film
• Emerald crabs, valued for eating bubble algae that few other tank residents will touch
• Porcelain crabs, filter feeders with an almost comical habit of waving their feathery arms through the water

Snails and other quiet workers

Snails rarely win a popularity contest, but a tank full of turbo and nassarius snails quietly patrolling the glass and sand has its own understated charm, and their constant grazing does more for tank cleanliness than almost any equipment upgrade.

A gentler side of the reef

• Sea stars, slow moving and oddly hypnotic to watch cross the glass
• Feather duster worms, which unfurl a delicate crown to filter feed and retract instantly if startled
• Sea cucumbers, unglamorous but effective at keeping the sand bed healthy

A few care basics before adding invertebrates

• Add invertebrates only to a tank with no history of copper based medication, since copper is lethal to most of them
• Introduce new invertebrates only once some algae has grown in the tank, so they have something to eat immediately
• Watch hermit crab numbers carefully, since overcrowding can lead to them attacking snails for empty shells
• Acclimate slowly using a drip method, since invertebrates are generally more sensitive to sudden changes in salinity than fish

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