Building a successful reef tank requires a lot of research and hard work. But, as we aquarium hobbyists know quite well, the journey is extraordinarily fulfilling.

However, it is important to know from the outset that the work is never done. Performing routine tank maintenance is crucial if you want your aquarium inhabitants to 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 system, 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.

Clean-up crews commonly consist of snails, crabs, shrimp, urchins, sea stars, sea cucumbers, conches or pretty much any animal that will consume detritus and algae. For many hobbyists, clean-up crews are among the first animals added to a tank after it completes the aquarium nitrogen cycle.

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. Most of the aforementioned 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, shrimp and conches are a few well-known inverts that will consume detritus in a reef tank.

Your sand bed is a magnet to detritus build-up and can be difficult 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 consuming detritus. They also stir up the sand bed helping to keep waste and debris suspended making it easier for your filtration system to remove.

Sand Sifting Starfish

Algae grows in just about every reef aquarium, often in unreachable areas between your tank walls and rockwork. There are a variety of cool tools to help remove it, although it’s tough to keep up even if you tidy your tank on a regular basis. Mixing saltwater and topping off your tank with reverse osmosis water will help, as well as keeping your aquarium water parameters stable and at ideal levels. Having an in-tank clean-up crew who continuously focuses on algae removal is another safeguard you can add to prevent algae from becoming a major nuisance. In my experience, crabs, snails, starfish, urchins and sea cucumbers are the most effective.

A question often posted to message boards and posed to our staff asks, “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.

The following animals are the most popular clean-up crew critters you’ll find in a mixed reef tank:

Nassarius Snail


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 variety of snails available in our industry, with each performing a different task within the circle of life inside your tank. Turbo Snails, Margarita Snails and Trochus Snails scavenge rock and glass for algae. Nassarius Snails eat detritus and leftover food yet spend most of their time buried in your sand bed. When food enters the water and they emerge to eat, they sift and oxygenate the sand bed which is actually quite beneficial.

Then you have the “do-alls” of the reef clean-up crew like Cerith Snails that eat algae, detritus, leftover food and fish waste.

Emerald Crab


Another staple to aquarium clean-up crew are crabs. Crabs serve a vital purpose in the ocean’s food chain, although not everyone agrees they belong in a reef tank. Hermit crabs are the most common crab found in clean-up crews because they are affordable, entertaining and have an insatiable appetite for detritus, leftover food and even some types of algae.

Scarlet Hermit Crabs, also known as Red-Legged Hermits, are among the more peaceful species of hermit crabs. They are excellent scavengers and stay small so they can fit almost anywhere and are less of a threat to its tankmates. The Blue-Legged Hermit Crab is another popular reef safe hermit crab. They are productive cleaners but are known to be hostile.

Emerald Crabs are a great addition to any reef tank with bubble algae problems, although they mainly feed on leftover fish food and meaty foods. They have a bit of an attitude though and will prey upon small peaceful reef fish, so be careful when adding them to small tanks where the crab can easily catch fish.

Peppermint Shimp


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. Cleaner shrimp like the Skunk Cleaner can play an important role in your tank by cleaning parasites off fish and other living animals. Banded Coral Shrimp are another popular choice.

Aiptasia are a pest anemone prevalent in the saltwater aquarium hobby. They are regarded as a nuisance and often difficult to get rid of. Peppermint Shrimp are an inexpensive alternative to chemical solutions and will often consume these pesky glass anemones for you. In a well-fed aquarium, they may end up ignoring your Aiptasia and feeding upon leftover fish food instead, which is still helpful.

Asterina are small white starfish that reproduce quickly in saltwater aquariums. The handsome Harlequin Shrimp will eat any starfish it can in your tank, which can be super beneficial if you an abundance of Asterina stars.


Now that you know some of the primary clean-up crew critters, you may be wondering how many of each you need in your tank. You may read recommendations online which stipulate “one snail per gallon” or “one crab per four gallons,” although I find these rules too broad. To avoid overstocking your tank, I prefer a mix-and-match approach to address the specific biodiversity of your aquarium’s ecosystem.

For best results and to avoid overstocking, I suggest a conservative yet diverse base colony with a few of each of the key players and then growing your clean-up crew from there. If your tank develops an algae bloom, adding appropriate organisms to address the specific problem (as well as identifying the source) would be the way to go. If things get better in the coming weeks but you still see room for improvement, you might consider adding more of the same species or another animal known to feed upon whatever is ailing your tank.

Clean-up crew critters add a lot of life and movement to an aquarium. Watching crabs scurry about your aquascape and Nassarius Snails race each other up and down your aquarium walls brings a smile to any reefer’s face. Most clean-up crew members are easy to catch and remove. So, if the issue you were experiencing is no longer a problem, you can always round up the excess animals to place into another aquarium or share with one of your reefkeeping buds.

What animals do you have in your clean-up crew? Let us know in the comments below!