A well-balanced and diverse clean-up crew is an integral part of having a healthy and beautiful aquarium, whether it’s a reef or predator system. While there are many free critters that are a great part of your clean-up crew, such as various isopods and copepods, Asterina stars, mini-brittles, mysid shrimp, Stomatella snails, bristle worms, and other polychaetes, these are only a small (ha ha, pun intended as these are part of your microfauna) part of a good clean up crew. By diversifying the animals you add to your tank to consume both detritus and algae while also stirring your sand bed, you can help keep your water quality healthier and reduce the amount of cleaning that you have to do to keep your system looking good. A variety of snails, crabs, and echinoderms, which each have a different niche in your clean-up crew, will help to ensure that every nook and cranny of your tank is being cleaned in a natural way versus adding dangerous chemicals and algicides to attempt to have a sparkling environment. At Reef eScape, we can help guide you through purchasing the appropriate types and amounts of different animals to maximize your enjoyment of your aquarium.
Emerald Crabs – Out of the crabs in the saltwater hobby, emerald crabs, aka Mithrax Crabs, are the most reef-safe additions to your aquarium. These crabs are omnivores, but their primary diet is herbivorous. They have modified pincers that are flattened at the points adapted to pull algae rather than tearing flesh. Although all crabs will eat a meaty diet, these crabs are perfectly happy to exist on a diet of nuisance algae in your tank. Emerald crabs also lack the aggressiveness that most crabs have and tend to use aggressive displays to fend off predators, but they seldom follow through on threats. Emerald crabs are especially good at removing Valonia or bubble algae which has a tendency to grow in crevices in your rock and also on the inside of coral colonies. While an emerald crab can be housed singly, their docile nature means you can add multiples to your aquarium at the same time without fear of them killing each other off. You can even witness breeding behaviors in your aquarium by adding both male and female crabs (males have a thin telson or tail tucked under their bodies and females have a wide onion shaped telson) although their offspring will only result in some happy fish and corals due to a surprise crab snack after hatching. Emerald crabs also come in two colors, an emerald green color (hence the name) and a red color which can be a nice complementary color in your reef!
Blue Leg Hermits – Blue leg hermits are one of the smaller species available in the hobby. Characterized by bright blue legs with white “knees” and black and white highlights and black claws with white spots, these are colorful additions to any aquarium where they won’t make a quick meal for an aggressive fish. As with any crab, they are omnivores, but their small size keeps them very manageable in the reef aquarium. While larger hermit crabs can have a tendency to rehome snails from their shells to their stomachs in order to get a new shell for themselves, blue legs typically are neither large nor aggressive enough to kill snails in order to get a new home. Blue legs feast on a variety of nuisance algae, from cyanobacteria to film algae to shorter hair algae. When keeping hermit crabs in the aquarium, it’s also important to have a variety of shells for them to move into as they grow. Shells that are too small won’t be used by these animals, and shells that are too large will result in a hermit crab that cannot move itself around. In addition, a lack of suitable shells for them to grow into may also result in losing your crabs as they may abandon a shell that’s too small and end up as a tasty treat for another animal as their tails lack the hard exoskeleton that other crabs possess which is why they require a shell as a home.
Conchs – Conchs come in a variety of shapes and sizes, but there are several that are great additions to reef aquariums. Some popular conchs that are commonly available here at Reef eScape are the tiger sand and fighting conchs as well as the occasional and much larger milk conchs. All conchs are characterized by having an eye on a raised eye stalk. They also have a long proboscis that extends out beyond their body in order to graze on algae. Conchs are appropriate for aquariums that have open spaces of finer-grained sand in which they can live and eat. Because conchs have a heavier shell, once they grow beyond a smaller size, they cannot lift themselves off the glass, so if you don’t have enough algae within reach, they are likely not going to be appropriate additions to your tank. Conchs excel at eating algae and are often the best animals you can get for consuming cyanobacteria that are growing on your sand bed and the lower reaches of your rockwork. As an added bonus, conchs will also stir up your sand bed, helping to keep it loose and free of detritus. Conchs also have the unique ability to flip themselves away from trouble by using their foot and their opercular cover (the “trap door” that they will use to seal their bodies up in their shells to prevent predators from getting to their bodies) but be careful as they cannot flip themselves out from between rocks so make sure that your rockwork doesn’t have any areas that they can get trapped or wedged in.
Cerith – Cerith snails come in a couple of different varieties for the home aquarium, but both share the same habits and are useful for the reef. The Mexican Cerith is stockier and has a white tip at the end of a dark shell, and the Caribbean Cerith (often referred to as the Florida Cerith) has a longer, lighter-colored shell with ridges. Both of these snails stay fairly small, but the Mexican species stays much smaller than the Caribbean. These are often referred to as margin snails as they are great for stirring up your sand bed and also eating the algae that grows in the top layer of your sand and along the glass. If they do not have enough algae to eat in the sand bed, they are small enough, unlike the conchs, to pull themselves up onto the glass and the rocks to graze. While they specialize in film and other types of algae, they also consume leftover food and detritus, which is an added benefit for these great snails.
Astraea—Astraeas are great smaller herbivores for your glass and rock. These snails have a conical shell and will carve paths through the algae on your glass and rock. They are great at eating film algae but will also eat other types of algae. Due to their smaller size, they can get into places that other snails sometimes cannot get to. Be careful, however, as these snails typically cannot right themselves if they fall on their backs in a reef aquarium, especially in the sand.
Nassarius – Nassarius snails are excellent detrivores and interesting critters for your sand bed. They typically live just below the surface of your sand bed with only their “snorkel” or proboscis sticking out. The second food hits the water; however, they spring into action, shattering the stereotype of moving at a snail’s pace. These snails help to keep your substrate healthy and clean by stirring up the sand and freeing it up of excess food. This also helps your water quality by keeping detritus from settling down into the substrate. These come in a few different varieties, but they all do a great job of keeping your aquarium clean.
Bumble Bee – Bumble bee snails are great detrivores but are not averse to becoming active hunters of other snails and worms. These attractive snails stay very small and are characterized by a spiraling yellow streak on their black shells. They stay in the rockwork, hiding in cracks and crevices, and will hunt for food amongst the rocks. Sometimes, they will climb onto the glass, but most of their time is spent where their food source is the rocks. Bumblebee snails can be great additions to a tank that is suffering from vermetid snails as they can prey upon these, but don’t expect them to wipe out a population of them if you’re making other foods readily available to them. While utilitarian, these snails will not cure your tank of nuisance pests without other food sources, they help keep populations of unwanted hitchhikers in check and add a nice splash of color.
Trochus – Trochus snails are often said to be the best algae eaters in the aquarium, especially when it comes to hair algae, and are also some of the best snails you can get if you want them to reproduce in your aquarium. These snails are also among the only “glass cleaning” snails available that can flip themselves over if they fall onto the sand or their backs. They have an attractive black or brown and white spiraled pattern on their conical shells and pack a lot of bang for the buck. Be careful to avoid getting too many; however, as these snails can grow quite large, keeping them well-fed can become a challenge if you have too many in the same system. These snails also come from tropical water, so they are perfectly suited to the typical hobbyist’s tank, even for predator systems, given how strong their foot is.
Turbos – Turbo snails are a great addition to most aquariums. They are tough and durable snails that can withstand attacks from predators like triggers and puffers to mantis shrimp, given their shells' thickness. They are voracious algae eaters, but like the aforementioned Astraea, snails cannot right themselves if they fall onto their backs. While not deliberately destructive, these are powerful snails that can grow large and knock unsecured frags off your rocks. Turbos sometimes do not live as long as some other snails in the aquarium as they are typically collected from cooler waters. Some struggle with longevity because they are more temperate than tropical. That said, the ones we bring into the shop are ideally suited for your aquarium and will help keep your rock and glass clean and free of undesirable nuisance algae.