Clean-Up Crew 101: Snails, Hermits, Starfish & Algae-Eating Fish

Skip the guesswork. Our Clean Up Crew Calculator takes your tank size and what the algae is actually doing, then builds the crew from what is in our systems today with live prices. If the right answer is to buy nothing yet, it says that too.

A reef tank without a clean-up crew is a full-time job for you instead of a shared one. Snails, hermits, starfish, and a handful of algae-grazing fish handle the daily grind of eating film algae, sifting detritus out of the sand, and cleaning up leftover food — work that would otherwise fall entirely on manual scrubbing and extra water changes. Building the right crew, in the right numbers, at the right time makes everything else about running the tank easier.

Snails: The Backbone of Any Clean-Up Crew

Snails should be the first thing you add once diatoms show up in a new tank, and they’ll do more day-to-day grazing than almost anything else in the crew. A few species each cover different ground: turbo and astrea snails are the workhorses for film and hair algae on rock and glass, roughly one per 7–8 gallons; cerith snails work the sand-to-rock margin and can be stocked more densely, around one per 2–3 gallons; and nassarius snails burrow through the sand bed processing leftover food and detritus, also around one per 2–3 gallons in a tank with enough waste to feed them. Match the mix to what you’re actually seeing — a tank with more sand than rock benefits from more cerith and nassarius, while a rock-heavy tank leans more on turbo and astrea.

Blue Leg Hermit Crabs

Blue leg hermits are efficient scavengers and generally get along fine in groups, but they will squabble over empty shells if none are available — and a hermit that wants a snail’s shell badly enough may kill the snail to get it. Keep a handful of appropriately sized empty shells in the tank at all times to head this off. As a starting point, roughly one hermit per gallon works for most tanks, though many reefers run fewer once the crew is established and shell competition is well managed.

Starfish: Brittle Stars vs. Sand-Sifting Stars

These two get lumped together, but they’re not the same recommendation. Brittle stars (aside from green brittle stars, which can bother fish) are genuinely reef safe and useful — they scavenge uneaten food and organic waste from within the rockwork, mostly at night. True sand-sifting starfish are a different story: they need a large, mature sand bed to survive, and in most home tanks they strip the sand of the microfauna they depend on within weeks, then slowly starve. Brittle stars are a solid, low-risk addition to almost any crew; sand-sifting stars are best left out of anything smaller than a very large, well-established system.

Lawnmower Blennies

Lawnmower blennies have a reputation as algae eating machines, and individuals can take thousands of bites a day at film algae and diatoms. That said, results vary fish to fish — some readily go after hair algae, others mostly graze diatoms and detritus and leave hair algae alone. They also need an established tank with real algae growth to eat; drop one into a spotless new tank and it can starve, especially if it’s over-fed prepared food and loses interest in grazing. A useful crew member, but not a guaranteed hair algae fix.

Tangs: A Genuinely Utilitarian Fish

Tangs earn their popularity honestly — they’re some of the best dedicated algae grazers in the hobby and look great doing it. Yellow tangs and kole (bristletooth) tangs in particular use specialized teeth to comb hair algae and film algae off rock all day long, and a kole tang is a great fit for smaller systems where a full-sized tang wouldn’t have room. Keep in mind a tang that’s fed heavily on prepared foods will graze less — if algae control is the goal, don’t let feeding replace foraging entirely, and always size the tang to the tank it’ll grow into, not the tank it’s small enough for today.

Wrasses to Consider Early

Wrasses aren’t algae eaters, but several species pull real weight in a clean-up crew by hunting pests directly — a six-line wrasse will pick off flatworms and small pests most snails and crabs never touch, and it’s hardy enough to add relatively early once your tank has some rockwork established for it to patrol. Just add wrasses one at a time and watch for compatibility, since several species (six-lines included) can be territorial toward similarly shaped fish added later.

When (and How Often) to Add Clean-Up Crew

Don’t add a crew the day your tank finishes cycling — a freshly cycled tank has stable water chemistry but none of the biofilm, detritus, or microfauna a clean-up crew needs to eat. Wait for diatoms to show up (usually within the first few weeks to a couple months) as your signal that there’s something to graze on, then start with snails. Build the rest of the crew in layers over the following months as the tank matures rather than dumping everything in at once, and expect natural attrition over time — snails in particular have a limited lifespan, so plan on topping off the crew every 6–12 months rather than treating the first batch as a one-time purchase.

Our Clean-Up Crew Is Collected Right Here in the Keys

Every clean-up crew package we sell is collected locally in the Florida Keys — it goes straight from collector to customer with no middleman, no long-haul shipping stress, and no time sitting in a wholesaler’s holding tank. That means healthier, hardier animals that are already acclimated to Florida water conditions before they ever reach your tank. Browse our current clean-up crew packages to build or restock your crew.

Build the crew in the order the tank asks for it

Start with snails once diatoms appear, add hermits with plenty of spare shells on hand, bring in a brittle star or two rather than a true sand sifter, and consider a tang or kole for genuine long-term algae control once your tank has the room. Build the crew in layers, and plan to top it off every 6–12 months rather than treating it as a one-time purchase. Questions about the right mix for your tank size? Reach out, or shop our locally collected clean-up crew.

Match the Crew to the Problem You Actually Have

Don’t just buy a generic “clean-up crew pack” — figure out what you’re actually fighting first. Diatoms and film algae on glass call for turbo snails and nerites; hair algae responds better to a dedicated algae-eating fish or urchin; and sand-sifting duties (keeping detritus from building up in the substrate) are better handled by nassarius snails or a goby than by hermits, which spend more time bulldozing your rockwork looking for food. Overstocking any single species also just creates a new bioload problem once the algae they were added for is gone and they start starving.

Match the animal to the problem

What you are looking at	What actually eats it	What does not
Brown dust on glass and sand, new tank	Diatoms. Astrea and trochus snails.	Hermits. They will not keep up on flat glass.
Green film on the glass you wipe weekly	Astrea, trochus, tiger turbo.	Nassarius. They live in the sand and eat meat.
Long green hair algae, more than an inch	Nothing in a pack reliably. Fix nutrients first.	Adding more snails. You will starve them later.
Bright green bubbles, one at a time	Emerald crab. One per 30 gallons, no more.	Snails. They cannot break the bubble.
Leftover food rotting in the sand	Nassarius snails and hermits.	Grazing snails. They are not scavengers.
Sand going gray and compacted	Nassarius, cerith, a conch in a big enough tank.	Turbos. They stay on rock and glass.
Aiptasia spreading on the rock	Peppermint shrimp, with no guarantee.	Any snail. Aiptasia is not algae.
Coralline spreading, purple and hard	Nothing. Leave it. That is a good sign.	Scraping it off the back glass on purpose.

How many, honestly

Rather than a per-gallon rule, use what you can see.

• A tank under three months old with light diatoms. Five to ten grazing snails is plenty. Add more when there is visibly more to eat, not before.
• An established tank with a weekly glass wipe. Roughly one grazing snail per 5 gallons is a working starting point, adjusted by how fast the glass films over.
• A tank with a real algae problem. Do not buy your way out of it. Nutrients, flow and light come first. A crew maintains a clean tank. It does not clean a dirty one.
• Hermits. Fewer than you think. They knock frags over and they will kill a snail for its shell if you do not leave empty shells around.

What we will tell you not to buy

If you message us with a photo of hair algae and ask which snail fixes it, the answer is usually none of them, and the honest advice is to wait. Buying animals to eat a nutrient problem gets you a nutrient problem plus dead animals. We would rather lose the sale than sell you that. If your tank has been running under a month, buy almost nothing. There is not enough food in it yet. Come back when the glass films over in a week.

Build the crew from our Florida Keys clean-up crew for sale, conditioned in Key West and shipped UPS Next Day Air to the lower 48.