A well-planned reef cleanup crew (CUC) is one of the most effective tools you have for keeping your saltwater aquarium clean, stable, and beautiful. Instead of relying only on equipment and water changes, the right mix of snails, crabs, and other invertebrates quietly works 24/7 to control algae, detritus, and leftover food.

What Is a Reef Cleanup Crew and Why Do You Need One?

A reef cleanup crew is a group of invertebrates chosen to perform specific maintenance roles in your tank. When balanced correctly, they help:

• Control nuisance algae on rocks, glass, and sand
• Break down leftover food and fish waste
• Turn over sand to prevent dead spots and compaction
• Support overall water quality between water changes

Think of your CUC as your tank’s “janitorial staff.” They don’t replace good husbandry, but they dramatically reduce the work needed to keep your reef looking sharp.

For more on getting your system ready before adding invertebrates, see our guide on reef tank cycling basics.

Types of Cleanup Crew and What They Do

Algae-Grazing Snails

Snails are the backbone of most cleanup crews. Different species target different areas:

• Trochus and Astrea snails: Excellent for rockwork and glass algae.
• Nassarius snails: Live in the sand and emerge to eat leftover food and meaty waste.
• Cerith snails: Versatile grazers that work on rocks, sand, and glass.

Tip: Start with a moderate number and add more only if you see algae outpacing your current crew. Too many snails can starve once the tank is clean.

Crabs and Other Scavengers

Crabs and related invertebrates help with tougher scraps and tight spaces:

• Hermit crabs (small species): Pick at leftover food and film algae in crevices.
• Emerald crabs: Known for eating bubble algae and other problem growths.
• Cleaner shrimp and peppermint shrimp: Scavenge food, and some help with pest control.

Tip: Provide plenty of empty shells if you keep hermits to reduce the chance they’ll bother snails for their homes.

Sand-Sifters and Detritus Eaters

Keeping the sand bed oxygenated and free of buildup is crucial:

• Sand-sifting snails: Constantly burrow and stir the substrate.
• Sea cucumbers and conchs: Process sand and consume organic waste.

Tip: In newer tanks with light feeding, go easy on sand sifters so they don’t run out of food.

How Many Cleanup Crew Members Do You Need?

Old rules like “one snail per gallon” often lead to overstocking. A better approach is to size your crew based on:

• Tank age – Newer tanks have less natural food; start small.
• Bioload – More fish and feeding means more scavengers are helpful.
• Algae levels – Let visible growth guide how many grazers you add.

Start with a conservative crew, observe for 2–3 weeks, then slowly add more if you still see excess algae or detritus.

As your reef matures, you can fine-tune your mix. For stocking inspiration beyond invertebrates, check out our article on best beginner reef fish.

Maintenance Tips for a Healthy Cleanup Crew

• Acclimate slowly, especially sensitive snails and shrimp.
• Avoid sudden salinity or temperature swings.
• Supplement feeding with algae sheets or pellets if the tank is very clean.
• Research fish compatibility so predators don’t pick off your crew.

With a thoughtful, balanced cleanup crew, your reef tank becomes easier to manage and more stable over time. By matching the right invertebrates to your tank’s needs—and adjusting as the system matures—you’ll spend less time scraping glass and more time enjoying your corals and fish. For a deeper dive into long-term stability, don’t miss our guide on building a reef tank maintenance schedule.