By: Haley Fitch
2018 Writers Contest Winner!
When setting up your new saltwater aquarium, it is vital to include a strong clean up crew to take care of your tank in ways that we as the aquarist can’t. By nature, the invertebrates that make up our aquarium clean up crews are vital to establishing a healthy ecosystem as each organism fills a different niche in cleaning up after coral and fish. As aquarists, we do our best to keep the tank as clean as possible by scraping algae off the glass, siphoning and stirring the sand bed, removing dead fish and coral, and keeping the water as pristine as possible. Despite the (sometimes grueling) hours we spend on our tanks to make them look their best, we simply cannot reach every crevice, find every single thing that may die, remove every speck of algae, or get to every inch of sand bed. This is where the clean up crew comes in.
Researching clean up crews can be daunting. Each organism does something different. Everyone eats a specific kind of algae, cleans only specific surfaces, or may even only consume one specific food that you will need to replenish once they solve the issue that they were introduced to take care of. I hope that this article helps new hobbyists decide what invertebrates are good fit for their tank and will help it look its best. I will break everything into groups based on which algae, pest, or other problems that each takes care of. To start off, new saltwater aquariums will go through multiple algae blooms as it matures.
This is inevitable, and is to be expected. Having a strong clean up crew before these blooms appear can help minimize algae when the time comes. The first of these alga is diatoms. It presents as a brown or gold layer of thin algae on the sand bed, that sometimes extends to the rockwork. There are two ways inverts can diatoms. These include sifting the sand, or eating it directly. Because diatoms feed on silicates from the sand, it is important to have some sand sifters to keep the sand bed moving and aerated to it can naturally release all bound silicates as quickly as possible. Although they do not directly feed on diatoms, Nassarius snails (Nassarius distortus) and Fighting conchs (Strombus alatus and Strombus pugilis) are great at stirring the substrate and keeping it aerated. Snails that directly feed on diatoms include Astrea snails (Astraea tecta), Banded Trochus snails (Trochus niloticus), and Nerite snails (Nerita species). Cerith snails (Cerithium species) are the best of both worlds. These guys burrow into the sand during the day, and emerge at night to clean. They are able to keep the sand bed aerated while also directly consuming diatoms.
Next, many aquarists experience a cyanobacteria bloom. This needs to be corrected as soon as possible, as cyano can quickly take over an entire tank if left unchecked. Cyanobactia appears to be a deep purple or red slime that can grow over any surface, usually starting on sand. There are not many organisms that eat cyano, so you may have to try a few in order to find a clean up crew that works for you. Snails that have been reported to eat cyano include Ceriths and Nerites. Other animals that may eat it are Red Leg hermits (Clibanarius diguetti), and Blue Leg hermit crabs (Clibanarius tricolor). Although he does not eat cyanobacteria, my Caledonian cucumber (Holothuria fuscopunctata) does a wonderful job breaking up patches of cyano that form on the sand bed.
One of the most aggravating and common algae problems is hair algae. This is typically limited to rocks, and appears as long strands of green algae as the name implies. Thankfully, many organisms enjoy eating this. From the species I already covered, Nerite snails, Cerith snails, Blue legged hermits, Trochus snails, Astrea snails, and Red-legged hermits will all consume hair algae. In addition, all types of Turbo snails (Turbo species), Emerald crabs (Mithraculus sculptus), Pincushion urchins (Lytechinus variegatus), and Sea Hares (Dolabella auricularia) will mow this alga down.
The final alga I will cover is film algae. This is the one that we all spend time scraping from the glass every so often because it likes to grow where it can block our view of the tank. It also grows in thin green layers on live rock. Nerite snails, Cerith snails, Trochus snails, Astrea snails, and Turban snails (Tectus fenestratus) will actively keep film algae in check. Trochus and Turban snails seem to be the most efficient and keeping your glass clean. Sea Hares and Pincushion urchins will also eat film algae.
Moving on from algae, uneaten fish food and detritus are the next biggest concerns. For this category, there are a lot of cool, interesting invertebrates that you can choose from. Starting off with critters already covered above, Emerald crabs, Cerith Snails, Nassarius snails, Caledonian cucumbers, Red legged hermits, and Blue legged hermit crabs will actively hunt out every bit of food or detritus they can find. Another fun choice is Peppermint Shrimp (Lysmata boggessi). These are small pink shrimp that I will further discuss in the next section. Other shrimp that are beneficial are Fire shrimp (Lysmata debelius) and Skunk Cleaner shrimp (Lysmata amboinensis), both of which will also groom fish and pick off dead skin or parasites. All three of these shrimps will consume all uneaten fish food that they find. Another cucumber that consumes detritus is the Tigertail Cucumber (Holothuria hilla). These guys actually ingest sand itself, picking up any detritus (and rarely diatoms or cyano) trapped in it. Then, they digest these impurities and excrete clean sand in small pellets. They are amazing at keeping your substrate looking pristine. Because they are a cucumber, they can also squeeze into extremely small crevices under and around rocks where snails and crabs cannot reach. Lastly, Bumblebee snails (Engina mendicaria) look like small Nassarius snails, but reside on your rocks hunting down detritus and extra food. They have an extremely attractive
black and yellow striped shell. These guys will also be brought up in the next section.
Finally, I will go through a couple of ‘problem solvers’ many people add to their clean up crews. These are usually added to keep populations of pests in check and will double as a detritivore. For starters, Peppermint shrimp are amongst the most popular problem solvers. When buying live rock or corals, many aquarists unknowingly bring Aiptasia into their saltwater aquariums. These are small pink or brown anemones that have a harsh sting to aquarium inhabitants and can reproduce extremely fast. They are hard to control because of their quick reproduction. But, Peppermint shrimp will scour the tank looking for Aiptasia as they eat these anemones with excitement. Don’t worry, they won’t eat your other anemones! Another hitchhiker many people unknowingly house are bristleworms. They are small red and black worms with white ‘bristles.’ While these are amazing detritivores, these can inflict a painful sting to humans and fish. If your bristleworm population is growing and you want to cut it down a bit, an Arrow crab (Stenorhynchus seticornis) would be a good addition to your clean up crew as they enjoy ripping apart and eating these worms. Next, Vermetid snails can be another pesky hitchhiker. These look like small spirals with a longer tube on your rocks, glass, or equipment. They are usually pink or greyish brown in color. Coral is extremely irritated by the long strands of mucus they excrete and is sometimes killed by it. These can reach plague proportions if not taken care of. Thankfully, Bumblebee snails have been found to seek these out and kill them. For this reason, I believe every reef tank should have a handful of Bumblebees. The last pest problem solver I will cover is the Harlequin Shrimp (Hymenocera elegans. Harlequin shrimp only eat starfish. But, one problem some aquarists have is Asterina starfish. These mini starfish reproduce by breaking off a limb and regenerating a new body, so it is easy for their population to get out of control. Harlequins are an amazing way to keep them in check but must be fed a full-sized starfish every month or so. Most people use Chocolate Chip stars to feed their shrimp. In conclusion, a strong clean up crew is vital for the overall health of your saltwater aquarium. These inverts help keep our tanks clean in ways that we aren’t able to.
If you are experiencing algae blooms, be sure to find the underlying problem so you can correct it as your clean up crew takes care of eating existing algae. I have by no means covered all of the invertebrates available to hobbyists, in fact, your local fish store probably has a couple inverts in stock that I didn’t even get to mention in this article. But, I hope that this helped you get a sense and basic understanding of what to look for the next time you need to add to your tanks first line of defense against algae, pests, and detritus. There is a multitude of interesting, unusual, beautiful, and overlooked creatures aside from fish that are available to you, and thankfully most of them can benefit your tank in one way or another!