A well-planned clean up crew (CUC) is one of the easiest ways to keep your reef tank looking sharp and running smoothly. These snails, crabs, shrimp, and other small invertebrates help control algae, consume leftover food, and recycle detritus before it becomes a water quality problem. In this guide, we’ll walk through how to build a balanced clean up crew that matches your tank size, aquascape, and maintenance style.
What Does a Clean Up Crew Actually Do?
Not all clean up crew members do the same job. Choosing the right mix starts with understanding their roles. A healthy CUC can:
- Control algae: Many snails and some crabs graze on film algae, diatoms, and some nuisance species.
- Process detritus: Hermits, nassarius snails, and bristleworms help break down uneaten food and waste.
- Turn the sand bed: Sand-sifters help oxygenate the substrate and prevent dead spots.
- Clean rock and crevices: Shrimp and small crabs pick food from tight spaces your fish can’t reach.
Remember, a clean up crew supports your maintenance routine—it doesn’t replace it. Regular water changes, mechanical filtration, and good feeding habits still matter. For more on keeping nutrients under control, see our guide on reef tank maintenance checklists.
Picking the Right Clean Up Crew for Your Tank
There is no universal “X snails per gallon” rule. Instead, think in terms of tasks and tank maturity.
Core Cleaners Most Tanks Benefit From
- Trochus or Astrea snails: Excellent glass and rock grazers for film algae and diatoms.
- Nassarius snails: Live in the sand and come out at feeding time to eat leftover food.
- Cerith snails: Versatile cleaners that work on rock, glass, and sand.
- Cleaner shrimp (Lysmata spp.): Pick at leftover food and sometimes offer cleaning services to fish.
Optional Specialists
- Emerald crabs: Can help with bubble algae, but monitor them as they may nip at corals if underfed.
- Conchs: Great for sandy bottoms in medium to large tanks; they constantly graze the substrate.
- Urchins: Powerful algae eaters for mature systems; secure your rockwork and be prepared for them to move loose items.
Tip: Start with a modest crew and add more only if you see persistent algae or detritus. An oversized CUC can starve once the tank stabilizes.
Stocking also depends on your fish and aquascape. Aggressive wrasses or puffers may snack on small snails and shrimp. If you keep such species, focus on tougher options like larger snails and urchins. For help planning livestock combinations, check out our reef fish compatibility guide.
Long-Term Care and Common Mistakes
Clean up crew members are livestock, not disposable tools. With basic care, many live for years.
- Acclimate slowly: Use drip acclimation for inverts; they are sensitive to sudden salinity and pH changes.
- Feed the crew: In very clean tanks, supplement with algae sheets, pellets, or small meaty foods for scavengers.
- Avoid copper: Most inverts are highly sensitive to copper-based medications.
- Provide hiding spots: Rock crevices and caves reduce stress, especially during molts.
Over time, some snails and crabs will naturally die off. Instead of large, infrequent restocks, add a few replacements at a time based on what you actually see in the tank. If algae is under control and the glass stays clean for days, your CUC size is probably about right. For additional tips on stabilizing new systems before adding a crew, read our article on cycling a saltwater aquarium.
A thoughtful clean up crew makes reefkeeping easier, not harder. By matching species to specific jobs, stocking conservatively, and caring for them like any other tank inhabitant, you’ll enjoy a cleaner, healthier, and more stable aquarium for the long term.
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