Reef Tank Cleanup Crews: Snails, Crabs and More

Cleanup Crew. Tank Janitors. Tank Cleaners. Functionally, it means the same thing to every hobbyist…. inverts added to your tank to keep it nice and sparkly.

It’s a necessity (Well, not an absolute necessity)

Everyone has one.

But, if you ask those people what critters to include, and how many…. you’ll get many MANY different answers.

So, Great!~ Renee is going to tell you exactly how to stock your tank. Naw! You knew it wasn’t going to be that easy. I hope to give you some things to think about and even some new information for some, to assist you when selecting your animals.

Grab your hip waders and let’s get some inverts!!

What you stock your tank with will depend on the individual needs of your tank. I know…… sketchy answer. But here’s how I would go about it…….

If you’ve been looking online for a vendor to buy your cleanup crew from, you’ve undoubtedly run across the complete packages many have up for sale. For the most part, they provide too many critters for the listed tank size and some critters are inappropriate to include in a complete janitorial package. Pass these packages by if they state there are no substitutions allowed.

Many of these packages include “algae busters” such as the herbivorous Lawnmower Blenny. No fish should be added for the sole purpose of being a part of the cleanup crew. Any fish should be considered with your fish stocking scheme rather than the cleanup crew stocking list. Other critters that frequently show up in package deals that should be considered on an individual basis and not an incidental inclusion are animals such as:

•   Brittle or Serpent Star
•   Lettuce Nudibranch
•   Sea Cucumbers
•   Sea Hares
•   Crabs, just as the Sally Lightfoot and the Arrow
•   Shrimp, such as the Peppermint or Coral Banded.

Your initial clean up crew should not include any of these inverts. They should be added as needed and researched individually.

So what should you stock your tank with for a basic Clean up Crew? Snails….. and a nice variety of them.

Usually, people add their crew first thing after the cycle and before the fish. How can you even begin to know what your tank will need at this early stage? So, instead of fully stocking your crew, half stock. You want the crew to cover all the different nuisance “algae”. What you don’t want is all the same snails competing for the same food and subsequently starving, while other algae grow unchecked. So mix it up! I put “algae” in quotations, as I am going to throw cyanobacteria into this loosely labeled group.

The Common Crew

These basics are appropriate for most any tank. None require any special care besides maybe daily flipping or returning a little “El Chapo” back to the tank. They are usually affordable and available and pretty hardy, which makes them a great selection for everyone.

Nassarius distortus (Nassarius Snail)

I love Nassarius. They are obligate scavengers on meaty foods….. dropped foods…… dead/dying….. they are with the program. A bare bottom tank won’t cut it with these guys, as they like a nice sandbed. You generally won’t see them until you feed the tank. Then they’ll be popping up from the
substrate like a jack in the box. Other than that, all you’ll see is their siphon above the sand. They won’t do anything for your algae besides reducing the fuel to grow them. In addition, as they clean up the leftovers they have the added benefit of agitating the live sand. After having sung their praises, I really wouldn’t keep more than a couple. They have big appetites and can be quite irritating to your fish if they are hungry. They’ll also strip your sandbed of its awesome critters.

Nerita spp (Nerite Snail)

Nerites are wonderful little snails and love film algae, such as diatoms (Helen, 2015). They do a great job on those glass/acrylic panels and some varieties will be seen cleaning the rocks as well. The above pictures show the Pacific variety, while the pictures below show the Caribbean. I have found the Pacific variety are the most desirable of the two. I placed both in my tank at the same time and within a few months, none of the Caribbean were still alive. A couple of years later and I still have all, but one of the Pacifics. Our oldest nerite is 10 years old. Both are intertidal and therefore have no problem “leaving” the tank. I have found the Caribbeans far FAR from the tank, traveling over yards of carpet. I have never had this problem with the smooth variety. Additionally, there are threads on the forums addressing the determination of the rippled variety in abandoning ship.

One thing nerites are known for, are their eggs. The bigger the snail the larger the eggs. The Caribbean variety can have capsules like grains of rice! Nerites haven’t been known to breed in our aquariums, so I would remove them from the panel as they appear. They can be difficult to remove after a while and require scraping. I do not find these snails to be desirable because of such, as it can become quite unsightly. There is also a huge size difference, with the Caribbeans becoming much larger than their smooth counterparts.

Astraea tecta (Astraea Snail)

I should start by saying that is not a misplaced “a” you see in my spelling of Astraea. Many people mistakenly drop the “a”, but it is after all only a common name which doesn’t require precise spelling. Astraea are very common and effective. They will eat green and brown film algae and may even pick at hair algae, BUT they require a little maintenance. You have to be willing to go through the daily (and often nightly) “righting” of these snails. They come from an environment where there is little risk of them

being flipped over on their back, so they have not developed the ability to right themselves. I also do NOT recommend them WITH hermits (who I’ll discuss in more depth later). Hermits are meat eaters. It’s just who they are, as none are obligate algae eaters. Add a snail that can’t right themselves and lunch couldn’t be easier. You know your own self….. will you want to add this chore to your daily ritual? If you know you won’t, pass these guys up and choose another. There are lots!

Cerithium spp (Cerith Snail)

Ceriths will eat film algae and diatoms and it has been said that they will eat cyano. They will graze on detritus but cannot consume filamentous varieties of algae. They can be seen both cleaning panels and cruising over any structure in your tank. They tend to be more active at night and help aerate the substrate when they burrow into the sand. You have to be careful when adding these into an environment with hermits, as the shape of their shell is highly valued by the crabs.

Ceriths are another snail that has visible eggs without actually producing offspring. As can be seen below, they can have a neat pattern on the glass, a messed up version on the glass or a total mess on the rock.

Just because I think ceriths are so ideal, here’s another picture showing they can be found anywhere….. even stirring your sandbed!

Trochus sp (Banded Trochus Snail)

Trochus eat a variety of algae from filamentous to film and has been reported to have a special adoration for diatoms (Amos, 1996). They can be found cleaning any surface in your tank, but frequently will be seen on the glass. They provide a similar function as the large turbo snail without the size, and therefore, are an excellent addition to your basic cleanup crew. They do reproduce within our tanks via a spawning event, and in a couple of months, you may see the juveniles on the glass. The juveniles may be mistaken for Collonista snails, yet upon close inspection, you can see the difference.

Tectus fenestratus (Turban Snail)

The Tectus snail will clean film algae, diatoms, and cyano from both the live rock and the panels. They are found in holes and crevices in their natural environment, so they have the ability to right themselves. These snails also go through a spawning event without eggs ever appearing in your tank.

Big Things Come in Small Packages

There are a group of smaller snails available from Florida collectors that shouldn’t be overlooked. Sometimes it’s the little guys that are the Power Horses. Note their size next to the dime.

Planaxis

These guys mainly live in shallow water under rocks, until it’s time to forage. That’s when you’ll see them out actively cruising around for micro algae. These are great little herbivores to add to your collection.

Dwarf Cerith

These guys will mainly hang out on your rock and the glass. They are excellent at controlling diatoms, cyano, film algae and detritus.

Nassarius vibex

The vibex can be like little sharks when they smell food in the water. Sometimes even the scent of your hand in the water column is enough to peak their interest. These guys are not algae eaters. They are excellent little sand stirrers and clean up carrion. They can also smell when something is about to die and they do not apologize for showing up early for the goodbye party.

The Beasts

I don’t consider any of these a part of a standard clean up crew. Most require a lot of food or are too large for many home aquariums. Some require supplementation with seaweed.

Turbo fluctuosa (Mexican Turbo Snail)

These are one of the smaller of the turbo snails, but make no mistake they indeed belong in the “Beast Category” and require a lot of food. They can indeed help you battle a hair algae outbreak, but remember to consider what happens once the algae have cleared. It’s smaller size is deceiving, and they have earned their nickname “The Bulldozer”.

Megastraea undosa (Top Crown Snail)

Most people know these snails by the genus Astraea, except this taxonomy label is no longer accepted and Megastraea has taken its place. The trusted database, the World Register of Marine Species confirms this change.Their size has earned them a spot in this group and it’s been reported they grow upwards of 6″. Keep in mind one place they are collected is in the waters around California. That puts it in the “prefers colder water” category. These snails are used in the food industry as an abalone-type substitution. They have been observed eating coralline off the rock in the ocean, so consider that if you have coralline you’re trying to preserve. They are a herbivorous generalist and eat microalgae and diatoms in addition to more filamentous algae.

Turbo sp (Zebra Turbo Snail)

These can grow to a massive MASSIVE size. When they are young and small, they are perfect for combating hair algae. If there was one snail only that could carry the name Bulldozer, this would be it. Maybe make arrangements with your LFS to trade in the snail when it gets too large, so you can start over with a smaller model. I would pick one of the others that are more appropriately sized, if given the choice.

Strombus sp (Queen Conch)

The Strombus is the court jester when considering entertainment value, as their antics make for an interesting show. They are fabulous at consuming filamentous algae. That sounds awesome, except for one issue….. their adult size. These guys can get upward of 12″ and can take down everything in its path with its clumsiness.

Strombus sp (Fighting Conch)

This strombus is a much more appropriate tankmate. They max out at about 4″ and are a peaceful snail, except may show some aggression towards other males. As mentioned, the Big Boys require lots of food, so supplementation may be required.

Hitchhiker CUC

Stomatellas are great, but are traditionally found as hitchhikers and not for sale. Ask a friend to share and keep an eyeball out at the LFS. If you see them cruising around their tanks, ask if you can have some. You do not have to worry about them successfully breeding in captivity because they WILL multiple… ALOT. Just a few and you’ll have much more. The snails will climb to a high point in the tank (usually) and simultaneously release their eggs and sperm into the water. You will not see their eggs.

Collonista spp (Collonista Snail)

Collonista snails are awesome. If you see a few in the daytime, peak into the tank in the middle of the night or at sunrise….. you’ll see those few have quite an extended family. There have been a couple (literally) threads I found on the forums, saying they were a problem for equipment, but generally everyone loves these guys. Again, ask a friend to give you a starter culture of about 5 to get your population going. And always remember to share with someone else who may be needing a starter culture once you get yours going. Pay it forward. You will not see the eggs of these guys, but you will see them spawning.

Columbellidae (Columbellid Snail)

I remember when they busted onto the scene as nano conchs. These became very desirable and for a while was being afforded a large price tag…. well, large for a hitchhiking nano-sized snail. Probably the best part were the eggs. Not only were there eggs, which is cool, but those eggs produced viable offspring.

Snails to Avoid

Engina mendicaria (Bumblebee Snail)

Avoid a large population of Bumble Bee Snails. They are whelks and are predatory on other small snails and worms. One or two in a tank are OK for decorative purposes, but remember if you see them moving up the glass, they are not grazing on the nasty algae…. they are looking for meat.

Margarites pupillus (Margarita Snail)

Another snail to avoid is one commonly present in online cleaner packages and at the LFS, is the Margarita Snail. These critters are from cold water areas and will slowly die in your tank over weeks to months. It doesn’t make a difference how they justify it or if they say there are some are from warmer waters (and of course it’s those they’re trying to sell you), they aren’t. They simply aren’t. So, it’s up to you if you want to place a cold water animal in your warm tank. They do not reproduce in our tanks and they do not lay visible eggs.

Babylonia sp (Fancy Nassarius)

Fancy Nassarius, Leopard Nassarius, Speckled Nassarius, no matter which way you say it, it all says the same thing, you’re being mislead. I’m not saying this is always done intentionally, but either way, such as it is. This is a Babylonia sp and they don’t even share the same superfamily! These are predators and they’re wanting to eat the stuff in your tank you paid money for!!! They will eat other snails, when given time.

Haliotis spp (Abalone)

Yes, it’s a snail. Not your average looking snail, but a snail none the less. This beauty lands itself in the “don’t buy” section because it really prefers cooler temps than is found in our tanks. Its beauty will mostly be out of view as it’s a nocturnal critter and is a master at hiding in crevices.

Pests of Snails

Pyramidellidae (Pyramid Snail)

Pyramid snails are not just for clams. I’m sure you have heard it rumored that if you see them on your snails, that variety won’t bother your clams and vice versa. This is one of the rumors that have turned into a fact on the forums, but it simply isn’t true. None of the snails in different studies chose to starve when there was another food item in the tank. They have preferences and will stay on that food item until it is 100% consumed, but then they would move on to another item and so on.

Polycladida (Polyclad Flatworm)

These flatworms cause as much havoc as the pyrams above. They too eat molluscs, which includes our ornamental clams and hard working snails. They are hard to remove as they can fall apart creating many more flatworms to grow and hunt.

Hermit Crabs

In my opinion, there is no such thing as a reef safe hermit. There are safer choices, but none are to be trusted. With the right variety of snails, you will never need a hermit. How can you trust anything that lives in a cerith, astraea or trochus shell? They are omnivores. That’s not just potatoes folks, that’s meat and potatoes. I know they are listed as herbivores on many sites… I don’t know what to say besides these sites are mistaken.

So, let’s talk about reef-safer hermits.

Scarlet Hermit (Paguristes cadenanti)

This hermit is frequently seen for sale and tends to be a little more expensive. They eat all kinds of algae, but remember he is an omnivore.

Left-handed Hermit (Calcinus laerimanus)

They are often referred to as Micro Hermits, Hawaiian Reef Crabs or the Dwarf Zebra Hermit. They don’t grow as large as the others, making them a safer choice.

Blue-legged Hermit (Clibanarius tricolor)

They really like the greens, but have been known to steal an astraea shell or two.

Buy only what you need and what is appropriate for your tank. They are only one part of solving an algae problem and are more for maintenance than a band-aid to a problem.

References:
Amos MJ. Management policy for the trochus fishery in the Pacific. In: Lee CL, Lynch PW, editors. Trochus: Status, Hatchery Practice and Nutrition; 6–7 June 1996; Northern Territory University. Canberra: ACIAR Proceedings; 1997. p. 164–9.

Heller, Joseph. (2015). Sea Snails: A Natural History. Cham, Switzerland: Springer.

There are a group of smaller snails available from Florida collectors that shouldn’t be overlooked. Sometimes it’s the little guys that are the Power Horses. Note their size next to the dime.