How to Acclimate a Cleanup Crew: Snails, Hermits and Stars

The box comes off the UPS truck, you float the bags, and twenty minutes later you have a bucket of snails that will not move, hermits pulled deep into their shells and a starfish that looks like it has given up. Most of the time all of that is normal. A cleanup crew spends a night sealed in a bag, and the way you bring it out of that bag decides whether it settles in by the weekend or starts dying off one animal at a time.

This guide covers the whole crew: snails, hermit crabs, emerald and arrow crabs, shrimp, urchins, starfish and sea cucumbers. The method is the same one we use on every invert page on this site. What changes from animal to animal is how slow to go, how to move it and what it does in the first two days.

The short answer

Fish are different. They get a shorter drip, 30 to 45 minutes, and our fish acclimation and quarantine guide explains why. Corals are different again: they don’t need a drip at all, and our coral acclimation and dipping guide covers them.

What the bag went through

Our livestock ships UPS Next Day Air on Tuesdays and Wednesdays, so your crew has spent about a day sealed in a bag of our water. Three things changed in that time:

• The temperature drifted toward whatever the box sat in. Floating the bag fixes that, and that is all floating fixes.
• The animals breathed out carbon dioxide, which pushed the pH of the bag water down.
• Their waste built up as ammonia. At that low pH most of it sits as ammonium, the less toxic form.

The moment you open the bag, the carbon dioxide escapes, the pH climbs and that ammonium turns back into toxic ammonia. That is why acclimation has a time limit as well as a minimum. A slow drip protects animals that can’t handle a fast salinity change. A drip left running for two hours in a bucket with no flow and no light keeps them sitting in water that is getting worse.

Why inverts get a slower drip than fish

Invertebrates are far more sensitive to salinity changes than fish. A fish holds its own body salt steady, so a quick change costs it some effort but rarely kills it. Of the crabs, shrimp and snails, shrimp are the touchiest about salinity and pH. Starfish, urchins and sea cucumbers are the most sensitive of all. They are osmoconformers: their body fluids follow the salinity of the water around them, so a fast change reaches every cell at once. That is why we give them the slowest drip of anything we sell.

Floating alone doesn’t solve this. It matches temperature and nothing else. Tipping snails straight from the bag into the tank after a float hands them the whole salinity change at once.

Step by step

1. Lights off. Turn the tank lights off and dim the room before you open the box.
2. Float for temperature. Float the sealed bags in your tank or sump for 15 to 20 minutes.
3. Open into a clean container. Use a bucket or tub that has only ever held aquarium water. Pour in the animals and their bag water. If they aren’t covered, tip the container so they are. If your order mixes starfish, urchins or cucumbers with snails and crabs, give the echinoderms their own container so you can run them longer.
4. Start a slow drip. Run airline tubing from the tank to the container and slow it with a valve or a loose knot to about a drop or two a second.
5. Time it. Snails, hermits, crabs and shrimp: 45 to 60 minutes. Starfish, urchins and cucumbers: about an hour, and longer if your salinity is far from ours. By the end the water volume should have roughly doubled twice.
6. Move the animals, not the water. Lift each one out by hand, net or cup. Move starfish, urchins and cucumbers in a cup of water so they never cross the air. Set snails right side up on rock or sand.
7. Throw the container water away. Never pour it into your tank.
8. Leave the lights off for the rest of the day.

Check salinity with a refractometer if you have one. If your tank runs on the low side, as fish-only systems often do, go slower, not faster.

Animal by animal

Animal and drip	How to move it	Normal in the first 48 hours
Snails (cerith, nassarius, fighting conch) 45 to 60 min	By hand, set right side up. Nassarius and conchs go on the sand	Staying shut and not moving for a day or more. Nassarius disappearing into the sand
Hermit crabs 45 to 60 min	By hand, onto the rock	Hiding and not moving much. A hermit getting ready to molt can sit still for hours
Emerald and arrow crabs 45 to 60 min	By hand or net	Hiding deep in the rock for a few days
Shrimp 45 to 60 min, long end if salinity is off	Net or cup, kept in water	Lights stay off for the rest of the day
Urchins About 60 min, slowest	Cup of water, never through air. Mind the spines	Losing an occasional spine. Heavy shedding is not normal
Starfish About 60 min, slowest	Cup of water, never through air	Not moving for days
Sea cucumbers About 60 min, slowest	Cup of water, never through air. Cover pump intakes and overflows first	Keep the intakes covered

Snails

Snails often come out of the bag looking dead. They pull in during shipping and can stay closed and still for a day or more after you add them. Give them that time, and acclimate them even if they look dead.

Place every snail right side up. Snails can’t always flip themselves back over, so don’t leave one on its back on the sand. Nassarius are scavengers that live buried, so one that vanishes into the sand on day one is doing exactly what it should. It comes up when there is food to scavenge. Fighting conchs belong on the sand too. Lettuce sea slugs go in the same 45 to 60 minute group.

To tell a resting snail from a dead one, pick it up and smell it. A dead snail smells bad, and you’ll know it the moment you do. Pull it out and don’t put it back. If there is no smell, set it back right side up and wait.

More on each: cerith snail care, nassarius snail care, fighting conch care and lettuce sea slug care.

Hermit crabs

Hermits get the same 45 to 60 minute drip. Once they’re in, expect them to hide. A hermit that sits still for hours may be getting ready to molt, so leave it alone rather than poking it to check.

The thing that matters most for hermits happens after acclimation: shells. Put a handful of empty shells in the tank, a little larger than the ones they’re wearing and in a few shapes. A hermit that outgrows its shell and finds no spare is the one that goes after a snail. Spare shells make that much less likely.

Our scarlet reef hermit crab guide covers diet, molting and shell choice, and reef safe crabs compares the crabs we carry.

Emerald crabs, arrow crabs and shrimp

These go in the 45 to 60 minute group with the snails and hermits. Of the three, shrimp are the touchiest about salinity and pH, so if your tank and the bag water read far apart, give shrimp the long end of the range. Move shrimp in a net or a cup and keep them in water.

Crabs often head straight into the rock and stay out of sight for a few days. That is normal.

Guides: emerald crab care, arrow crab care and Pederson cleaner shrimp care.

Urchins

Urchins are echinoderms, so they get the slowest drip: about an hour, longer if your salinity is well off. Move them in a cup of water and handle them with care, because the spines are sharp.

Watch the spines over the first week. An urchin drops the occasional spine all the time, and a few on the sand mean nothing. Heavy shedding is a stress signal. Check salinity and water quality first, and make sure it has something to graze.

Guides: pincushion urchin care, slate pencil urchin care and reef urchin care.

Starfish

Starfish, along with urchins and cucumbers, take salinity changes worse than anything else in a cleanup crew. Give them about an hour of slow drip, and longer if your tank and the bag water are far apart. Never lift a starfish out through the air. Scoop it into a cup with some water and pour the cup gently into the tank.

A new starfish may hide and barely move for days. Look at it, but don’t dig it out. What you are watching for is tissue that looks like it is wearing away or falling apart, which is a real problem. Hiding is not.

Some starfish guides call for a drip of two to four hours. We respect the caution, but we stay with about an hour and stretch it only when salinity is far off. The longer the animal sits in a bucket of opened bag water with no flow or light, the more the rising pH works against it. Our brittle star care guide has the rest.

Sea cucumbers

Cucumbers get the same slow drip as starfish and urchins. The difference is what you do before they go in. A stressed or injured cucumber can release a toxin that can kill fish, and one way a cucumber gets hurt in a home tank is being pulled onto an uncovered pump intake or into an overflow. Cover your intakes and overflow before the cucumber goes in, and keep them covered.

Move it in a cup of water, set it on the sand, and leave it alone while it settles. If a cucumber dies or gets caught in a pump, take it out right away and watch your fish closely.

Mistakes we see, and what they cost

Mistake	What happens	Do this instead
Floating, then tipping the bag in	Temperature matches, salinity doesn’t. The animals take the whole change at once	Float, then drip
Pouring the bag water into the tank	Ammonia and whatever came with it go into your system	Move the animals by hand, net or cup. Throw the water away
Letting the drip run for hours	The animals sit in opened bag water as the pH rises and ammonia gets more toxic	45 to 60 minutes, about an hour for echinoderms
An air stone in the bucket	pH rises fast and ammonia turns toxic	No air stone, unless you have added an ammonia binder first
Snails dropped upside down	Some can’t turn back over on their own	Set each one right side up
Lifting a starfish through the air	Stress on an animal that handles change worst of all	Move it in a cup of water
Adding a crew to a tank that has had copper	Snails, crabs, shrimp and echinoderms die	Keep copper out of any tank that will hold inverts
Calling it dead too soon	Healthy snails and stars get thrown out	Give it a day or two. Use the smell test on snails

Where other guides differ from ours

Most sellers agree on the basics: float for temperature, then drip, and never add the bag water. Where they part ways is timing. Some list a total of up to two hours for sensitive inverts, one popular hermit guide gives 45 to 90 minutes, and some starfish guides ask for several hours. Those are reasonable people being careful. Our method sits at the shorter end on purpose, because the animals are sitting in opened bag water the whole time. If your salinity is far from ours, stretch the drip. If it is close, an hour is enough.

FAQ

The Underwater Gardener is a reef aquarium store in Key West, Florida. The cleanup crew animals linked on this page are collected by our team in the Florida Keys. Livestock ships UPS Next Day Air on Tuesdays and Wednesdays.