Which Clean-up Crew Critters Should You Have In Your Reef Tank?

Building a successful reef tank requires a lot of research and hard work. Experienced aquarium hobbyists know quite well, the journey is also extraordinarily fulfilling. Nonetheless, it is important to know from the outset that the work on your tank is never done. Ongoing routine tank maintenance is crucial if you want your aquarium to look nice and prefer that your aquatics pets not only survive but thrive.

Even though you may have a small arsenal of aquarium maintenance tools and all the filtration equipment you could possibly fit in and around your tank, there are still going to be areas inside your tank that you cannot reach or get clean enough. Fortunately, there are a bunch of cool little critters you can employ to help keep your tank clean for you. These animals are most commonly referred to as the aquarium clean-up crew.

What Is A Clean-Up Crew?

Clean-up crews mostly consist of snails, crabs, shrimp, urchins, sea stars, sea cucumbers, and conches. We could technically categorize some fish as part of the clean-up crew as well, but we like to refer to those fish as "utilitarian fish" and reserve the title of clean-up crew for those previously mentioned invertebrates. The reality is, any animal that will feed upon algae and scavenge the tank for detritus or decaying organic matter can be a beneficial member of the clean-up crew.  

For many hobbyists, clean-up crews are among the first animals added to a tank after it completes the aquarium nitrogen cycle.

Some people think an aquarium clean-up crew’s job is solely to eat up algae. True, it’s one of their most advantageous traits, but it’s also far from all a CUC does for your tank.

Your aquarium clean-up crew works all day every day to keep your aquarium clean. Leftover food, for example, is a problem aquarium owners both fresh and saltwater face. Leaving uneaten food in your tank to rot and decay contaminates your water and throws off your parameters which can be dangerous to livestock. Scavenging clean-up crew animals will scarf up surplus food in your aquarium before it begins to deteriorate.

Detritus is non-living organic matter (like fish waste) that exists in every saltwater aquarium and is nearly impossible to remove without the assistance of clean-up crew workers. Sea cucumbers, snails, sea stars, shrimp, and conches are a few well-known inverts that will consume detritus in a reef tank.

Your sand bed is an absolute magnet for leftover food and detritus and can be a real pain to keep clean. The good news is there are a variety of invertebrates like nassarius snails, sand sifting sea stars, and tiger conches that will dig, crawl and slither about your substrate in search of waste and leftover food. This movement through the sand bed will also stir things up, helping to keep waste and debris suspended making it easier for your filtration system to remove. 

Algae grow in just about every reef aquarium, often in unreachable areas between your tank's walls and rockwork. There are a variety of tools to help hobbyists manually remove that algae, although it can be tough to keep up even if you tidy your tank on a regular basis. Having an in-tank clean-up crew that continuously focuses on algae removal can be a big help in keeping that algae problem under control. Crabs, snails, starfish, urchins and sea cucumbers along with utilitarian fish like blennies and tangs are your best defense against nuisance algae. 

The Best Clean Up Crew Animals For A Reef Tank

A question often posted to message boards and posed to our staff - “What are the best clean-up crew critters for a reef tank?”

Different animals perform different duties and, while there is some overlap, our general answer is a combination of species works best to tackle some of the chores mentioned earlier in this article. A diverse clean-up crew will divide and conquer the gunk, funk, and junk in your tank.

Snails

Snails are the most likely addition to an aquarium clean-up crew. Something many of us don't discover until we’re in the hobby is that saltwater snails move much faster than one would imagine. Snails are natural scavengers that will eat algae and leftover food inside your aquarium. Snails also have the unique ability to clean algae off live corals without damaging them, arguably one of the best functions they can serve in a reef tank.

There are a wide variety of snails to choose from when stocking your tank, the idea is to get a variety that can fill the various niches in your tank.

Astraea Snails: Herbivore, eats mainly film algae such as diatoms and sometimes cyanobacteria. It may also pick at hair algae and other green algae.

Turbo Snails: Herbivore, eats mainly hair algae and other green algae. There are a few different snails that are called "turbo" snails, most commonly you will see the Mexican Turbo Snail (Turbo fluctuosa) and Zebra Turbo Snails (Turbo spp or Trochus spp). Many have reported the Zebra Turbo snails to do a very good job on hair algae. These snails can get large and many times knock over unsecured corals and rock.

Cerith Snails: Herbivore, will feed upon green hair and film algae within the tank. These snails tend to be nocturnal in nature and will hide in the sandbed during the evening (generally not recommended for bare bottom tanks).

Nassarius Snails: Carnivore, will eat uneaten food, decaying organics, and fish waste. The Nassarius snail is one of the best detritus eaters for an aquarium with a sandbed. It will bury in the sand to sleep. When it senses food in the aquarium, it will quickly unbury itself and feed upon and food that makes its way to the bottom of the aquarium. Spot feeding may be required for the health of these snails. Small pieces of mysis shrimp or other meaty foods are appreciated. Many times you can also find Tonga Nassarius snails which are a little large in size than the standard Nassarius snails.

Nerite Snails: Herbivore, will graze upon film algae mostly on the glass of aquariums. They tend to be more nocturnal and show almost no activity during the daytime. Given enough food and proper water quality they can breed in home aquariums. They reproduce by laying eggs on the walls of the aquarium.

Trochus Snails (Banded Trochus Snails): Herbivore, eats mainly film algae such as diatoms and sometimes cyanobacteria. Trochus tend to graze more upon the film algae than any other types of algae, but they may graze upon some green algae and may even graze upon hair algae or bryopsis.

If your tank does not have a lot of algae growth you may need to supplement your snails diet. The use of Algae Sheets wrapped around a rock (use a rubber band to hold the algae more securely to the rock) is a great way to do this.

Hermit Crabs

People tend to have mixed feelings about hermit crabs; some people love them while others stay as far away from them as possible. While they do a great job scavenging the tank, some hobbyists feel they can knock over and even prey upon corals or fish.

Hermit crabs are omnivores and opportunistic scavengers. Hermit crabs spend most of their day picking at the surface of rocks for food (probably algae), but when they sense meaty-type foods in the tank, they will go after it. This may be a dying animal within the tank or excess food falling to the bottom. Many times when they go after a dying animal this can be perceived as them attacking said animal. While they may occasionally go after a healthy occupant of your tank, most of the time they are simply cleaning up. 

Hermit crabs also love to change out shells and if there is a lack of choices for them, they may go after snails in the tank to get their shells. Keeping an abundance of empty shells of various sizes can help with this. You may even see hermit crabs fighting with each other over what they perceive to be the best shell in the tank.

Scarlet Hermit Crabs: Omnivore, will feed upon meaty bits of seafood, algae, and detritus. They will also sift through the sand some. They have red appendages and bright yellow eyes.

Blue Legged Hermit Crabs: Omnivore, will feed upon meaty bits of seafood, algae, and detritus. These hermit crabs tend to stay on the smaller side.

Dwarf Zebra Hermit Crabs: Omnivore, will feed upon meaty bits of seafood, algae, and detritus. These are one of the smaller available hermit crabs and thus they are less likely to go after medium to large sized snails.

Mexican Red-Leg Hermit Crabs: Omnivore, will feed upon meaty bits of seafood, algae, and detritus. These are another very active species and can do a good job grazing on algae within the tank.

Shrimp

Shrimp are another sought-after addition to the clean-up crew. They are fun to watch and get into nooks and crevices to eat detritus and leftover food that other inverts can’t reach. Shrimp are unique in they fill some niches the other clean-up crew animals cannot.

Skunk Cleaner Shrimp: Carnivore that will feed on ectoparasites and dead tissue on your fish. They will literally clean your fish and some fish love it so much, they stop by for regular cleaning. They tend to gobble up leftover flakes and pellet food as well, sometimes even stealing captured food from LPS corals which is why they can be pesky in a reef aquarium.

Peppermint Shrimp: Also a carnivore and belongs to the same genus as the cleaner shrimp, Peppermint shrimp fill another unique niche. Peppermint shrimp are favored because of their appetite for pesky aiptasia anemones but are also effective scavengers and occasionally cleaners. They poke about the rocks looking for leftover bits of food.  It should be noted, there are a few different species collected for the aquarium trade, and if you're looking for the one that targets aiptasia, the scientific name: Lysmata boggessi is the one you want.

Coral Banded Shrimp: Naturally they are carnivorous scavengers and will bounce about looking for leftover food, accepting frozen, flakes, or pellets in most aquariums.  They are active, showy shrimp that tend to be a peaceful member of most saltwater tanks. They can be aggressive toward other shrimp in the same aquarium, so just a single specimen is best. 

Harlequin Shrimp: A very cool-looking shrimp with a very specialized diet of sea stars. These are not for every tank and should only be kept if you can sustain their diet by propagating plenty of asterina starfish or cutting up and freezing chunks of larger sea star species to feed them. Most hobbyists don't think of these guys as clean-up crew critters but they can make quick work of an asterina star infestation.

Fire Shrimp: Another member of the "cleaner shrimps", the Blood Red Fire Shrimp are among the most striking inverts in your crew. They will set up cleaning stations to clean ectoparasites and dead tissue from fish while also scavenging the tank for leftover food.

Other Assorted CUC - Clean Up Crew Animals

Emerald Crabs: A very popular CUC member that is known to prey upon Bubble Algae and scavenge the tank opportunistically for its next meal. They are classified as omnivores and some hobbyists have witnessed them show aggression toward fish, shrimp, and other tankmates when they are left with nothing to eat. As long as you keep them well-fed with prepared aquarium foods (frozen or dry) they should be a peaceful member of the community. 

Sally Lightfoot Crabs: These omnivorous crabs can be a little aggressive but when kept well-fed, they should leave your fish and other small inverts alone. They do grow large and will benefit from a larger tank with a strong current and lots of places to hide amongst the rocks. They are known to graze upon algae or dried seaweed and should also be fed meaty bits of frozen food. 

Sand Sifting Sea Star: Carnivore, feeding upon sand-dwelling crustaceans like spaghetti worms, tube worms, copepods, amphipods, etc… While a great invertebrate to keep the sandbed thoroughly sifted, it comes at a price. They will decimate your sandbed off all living creatures. It is estimated that one Sand Sifting Sea Star can void a 5-inch sandbed in an 80-gallon system of living sandbed matter in just a few weeks. It will then proceed to stay hidden in the sand, starve to death, and decay. My personal recommendation is to leave these starfish in the ocean. While a few people do have success long-term with them, that is an exception and should be taken into consideration when thinking about purchasing one.

Serpent Star & Brittle Star: Carnivore, feeds upon meaty bits of seafood and detritus. They tend to hide in the rock work and all you see of them is their arms sticking out of the rocks trying to grasp at pieces of food as they float by. But some will venture out of the rock work and hunt down pieces of food in the tank after you have fed your tank. Be cautious of the Green Brittle Stars as they are known to go after fish of all sizes, but the other types of serpent and brittle starts are generally safe with all different sized fish and invertebrates.

Urchins: For the most parts urchins can be very useful in a reef tank. The Pincushion (Tuxedo) Urchin grazes upon all types of algae including coralline and will occasionally pick up loose pieces of rubble, sand, and even coral frags and "carry" them around the tank. The Longspine Diadema Urchin will also graze upon all types of algae and unfortunately will sometimes graze upon corals as well, specifically SPS corals like Acropora and Montipora. Proceed with caution in a reef tank.

Sea Cucumbers: Many types of cucumbers will sift through the sandbed and will digest the algae and detritus off of it. Some can get quite large and some are toxic if they die within the aquarium (avoid "sea apples"). Cucumbers can be on the more sensitive side, so I would recommend them to the novice hobbyist.

Nudibranch: The two most commonly seen nudibranchs available are Sea Hares and Lettuce Nudibranch. They can be useful in helping to rid a tank of Bryopsis or green hair algae in particular. They tend to be very sensitive to changes in water conditions, so you will want to make sure you keep your parameters stable for them. They can make quick work of the algae in a tank and starvation can quickly become a problem.

How To Choose The Right Crew

Now that you have the lay of the land, it's time to choose the right crew for you. You might read about some generic rules such as "1 snail per 4 gallons" or some version thereof. These rules can quickly lead to overstocking or just tend to be too generic and don't take into consideration the specific role each clean-up crew player has. 

The best approach is to get a variety, most certainly to include snails and a few hermit crabs. Beyond that, choose the shrimp, crabs, and other animals on an as-needed basis. Strict herbivores like Sea Cucumbers and Urchins or those with specialized diets like the Harlequin can easily starve if there is not enough food in your tank.  Most of the popular websites and quality local fish stores offer "Clean-up crew packages" that include a variety of snails and crabs based on tank size.  Ultimately the population will be controlled by available food sources in your tank. 

It is popular to start stocking clean-up crew animals early in the game, as soon as algae and other organisms begin to grow in your aquarium. While it can work to help keep some of that nuisance algae from getting out of control, be mindful of having enough food for the animals in your care.  You can always start conservatively and get more should you think you need them down the road.  Also, don't forget about utilitarian fish such as tangs and blennies which have the same effect while your tank is maturing, they can be highly effective algae eaters and should be considered when choosing your clean-up crew.