Posted by: joejaworski | October 3, 2013

What’s the Best Snail for a Reef Tank?


It seems that every couple of years a new marine snail appears in the trade that promises long life and consumption of every form of algae under the sun. The fact is, most all snails have a preference for a specific algae/detritus problem and choosing the right snail to solve your particular cleanup issue is key to getting these little guys to work for you.

If your tank is less than 4 months old, it will traverse in and out of cycles and you will likely see every algae/Cyano outbreak in the book. This is a normal process that could go on for 6 months or more until the tank finds an equilibrium and stabilizes itself. Many beginners rush out and buy one of the many “Reef Cleaner Packs”. These assortments don’t target the problem you have and usually contain way more snails then the algae in your tank can support. The result is usually a massive snail die-off from starvation. This results in an algae bloom greater than the initial problem you were trying to solve.

It’s not uncommon for established tanks to go through a bloom of algae on occasion. The usual advice is to cut back or stop feeding, do a water change, replace your RO or DI canister, add GFO/Carbon, dose this or that- and the list goes on. The fact is it may have happened without you causing it. Many tanks need to be fed daily in the case of non-photosynthetic livestock (some types of corals and most fish) and if you feed close to the same amount on the same frequency then that’s not the issue. Trying to find the source of the bloom is near impossible. It’s best to take the shotgun approach and just eliminate or reduce algae nutrients using all the methods that are posted all over the internet.

Even if you solve the problem some forms of algae will remain and not disappear. For example, Green Hair Algae and Bryopsis will sometimes stay in a sort of stasis and won’t grow anymore but won’t die back either. Using snails to consume these algae will remove them and, if water conditions have been fixed, they won’t grow back.

algae1With text book water parameters, you will still get algae. it’s impossible to keep a reef tank free of detritus and algae for any length of time. The trick is to find the right snails and the right quantity of snails to maintain the tank in good condition.  This reminds me of the story of painting the Golden Gate Bridge. It takes so many years to paint the bridge from start to finish that when it’s done, they need to go back to the beginning and start over again. Same with snails. The algae is never gone, but enough has grown back for the snails to go over the same spots again. Not enough snails and the algae will slowly take over. Too many snails and they’ll starve to death and pollute your tank. The best way to determine what you need is to start with a small number of snails. On a monthly basis, take a look at your algae and decide whether you need to add more.

In general, most snails are hardy creatures. But they don’t acclimate well. If you find that a day or two after you added a bunch of snails you see a few dead ones, then you need to increase the time for acclimation. Many folks also complain about snails being short-lived. This is usually the result of buying temperate water snails and keeping them in very warm tank water. A temperature of 78F is the upper limit for most all snails. Some won’t live long above 75F. If you’re tank temperature runs in the upper 70s to low 80s, the Astrea snail is probably the only one that can tolerate these temperatures.

As snails age, they tend to get weak and frequently fall off rock work. They don’t make much attempt to right themselves. If you see this behavior, place the snails in a place where you can keep on eye on it for a few days. If it hasn’t moved, it may bedead or near dead and its best to remove it from your tank.

Snails usually have a preferred algae, be it diatoms, hair, or film. It is their primary food source. They may eat other types of algae as well, but this is the one they go for first. While many snail types will eat Cyano Bacteria, there is no known tropical snail that prefers it. Therefore, relying on a particular species to eat Cyano is hit or miss.

While most snails can right themselves, The ability for a snail to do this is based on how far they can extend their mantle to reach an object to grab onto. If any snail is completely upside down surrounded by fine sand, it won’t have anything solid enough to grab and no snail can right themselves. The exception may be the Nassaruis where I have witnessed them twisting their shells around is a quick motion without being attached to anything.

Here’s a detailed rundown of the most widely available snails and their strengths and weaknesses.

Abalone (Haliotis sp.)

abaloneAbalones are like a giant Limpet. They have a single top shell and can grow to about 3 inches. If you buy one, make sure you purchase a tropical variety as most Abalones live in temperate waters. Because of their size, they are voracious film algae eaters. They will also remove coralline algae from smooth surfaces, but won’t consume it. They only eat film algae. Unless you have a very large tank and a horrendous film algae problem, they are not for you. They also have a sharp serrated appendage that flexes as it walks and have been known to scratch acrylic tanks.

Astrea Snail (astrea sp.)

AstreaAstrea snails are a good all around cleaner with large appetites. They prefer hair algae, but also consume green film, diatoms, and  Cyano. They won’t eat long strings or big tufts of hair algae, but if you cut it back to a “lawn” on live rock they will voraciously eat it. These guys require extra time in acclimation. However once acclimated, they can tolerate higher water temperatures than most snails. Astreas are good all around herbivores and are a good addition to any tank, especially those that suffer from hair algae outbreaks. If they fall off the glass or live rock into the sand they cannot right themselves and will eventually die. Their soft underparts will also get picked at by hermit crabs and fish furthering their demise.  For this reason, buy larger Astreas so they won’t fall into small crevices. Keep an eye on them. If they fall, be ready to move them from the sand bed to a place on your rock.

Bumble Bee Snails (engina sp.)

bumbeesnailThe Bumble Bee snail is very attractive with its black and yellow striped shell. This snail is a carnivore- it won’t eat any algae. It is a good sand sifter as it partially buries itself in the sand. It will eat detritus, bristle worms, and other organisms in the sand bed. It won’t decimate your sand microfauna like the sand sifting starfish can, but it will have some impact. These snails require an old established tank to do well. While the shell is attractive, it will eventually get covered with coralline and other algae. In general, the bumble bee snail may do more harm than good in a reef tank.

Cerith Snail (Cerithium sp.)

cerithDespite not being very popular, The Cerith snail is a great all around snail because it will feed on so many things. It is an omnivore so it will eat detritus, uneaten fish food, film algae, diatoms, hair algae and Cyano. It is also an excellent sand sifter as it will bury itself in the sand. They can grow to about 2-3 inches but they are very slow growers. They will lay eggs but reproduction in aquariums seem to be limited. Most aquarists don’t like them because they don’t appear very active. They are in fact true nocturnal creatures and will do all their work at night. These snails are perfect for established tanks to handle routine cleaning, and for new setups to keep various algae issues in check.

Cowrie (Cypraea sp.)

cowrieCowries are very attractive with their patterned glass like shells. However, they are not good additions to reef tanks. As juveniles, they will eat lots of detritus and sometimes algae, and they normally stay on live rock and don’t venture across the glass. As they grow they will pick at and consume smaller soft corals and anemones. They are attractive additions to a FOWLR tank, but I cannot recommend them for any reef tank containing soft corals, mushrooms, or anemones.

Margarita Snail (Margarites sp.)

margaritaMargarita snails are the best hair algae eaters. They have big appetites and can really clean up a tank fast. While they will also go after film algae, they prefer hair algae and will often starve if not enough is present. This is one snail I would not buy in large quantities because they will run out of food quickly. They tend to move up the glass often staying half-in / half-out of the water. They do not like warm temperatures. 76F is their max temperature for long term survival.

Nassarius Snail (Nassarius sp.)

NassariusNassarius snails won’t eat any algae- they are carnivores. They need fine sand and will bury themselves and move around keeping your sand bed clean. They will eat detritus and uneated food. Unlike the Bumble Bee snail, they don’t appear to eat the microfauna in the sand bed. They are small in size and can get into live rock crevices and keep it clean.

Nerite Snail (Nerita sp.)

neriteThere are actually more species of Nerites that live in freshwater than salt. Nerites are the diatom eaters. They also consume film, hair, and Cyano. They are small in size (maximum size is 1 inch) so they can get into hard to reach places. However, being small they do not consume algae as fast as other snails. Of all the snails listed here, they are the most long lived and will survive 3-5 years under good conditions. When stocked together with the Cerith, they make a great team in controlling algae in established tanks.

Trochus Snails (Trochus sp.)

trochusTrochus snails are large in size and big eaters. They are big on film and diatoms, but do not readily eat hair algae. They seem to be short-lived, but do spawn every few weeks in most aquariums. If your corals or rock work is not secured, they will act as a bulldozer and knock things down. Because of their size, do not overstock these as film and diatom algae may be in short supply down the road.

Turbo Snails (Turbo sp.)

turboTurbos are large snails that eat massive amounts of algae. They prefer film algae, but will eat all forms of algae including macro algae. Due to their size and weight they can knock over a significant piece of live rock or larger corals with ease. Avoid the “Mexican Turbo” variety as they are subtropical and won’t live very long in most reef tanks. It is important to watch for dead or dying Turbos as their large size can pollute a tank quickly. They eat so much algae so quickly, that I wouldn’t go with more than 1 per 25 lbs. of live rock. If you have any specialty macro algae, these guys will eat it.


So what’s the best snail?

It really depends on what  your major concern is:

Problem Best Snails
Film Algae Trochus, Nerite
Diatoms Nerite, Trochus
Hair Algae Margarita, Astrea
Cyano Turbo, Astrea
Detritus Nassarius, Cerith
Macro Algae Turbo, Trochus

Here’s a nice summary to use in choosing the snails for your tank:

Snail Film Diatom Macro Cyano Hair Detritus Right Themselves
Abalone x x No
Astrea x x x x No
Bumble Bee x Yes
Cerith x x x x x x Yes
Cowrie x No
Margarita x x x Yes
Nassarius  x Yes
Nerite x x Yes
Trochus x x x x Yes
Turbo x x x Yes





  1. The ability for a snail to right themselves is based on how far they can extend their mantle to reach an object to grab onto. If any snail is completely upside down surrounded by fine sand it won’t have anything solid enough to grab.

    Some snails (like Nassaruis) seem to have the ability to twist their shells around with being attached to anything.

  2. Great write up. Thank you!

  3. Great article, I’m going to share this with my readers.

  4. Blame it on the snails Sean…couldn’t possibly be bad husbandry, right!

  5. Thanks Joe. I’m new to marine tanks, and found your article a great summary.

  6. Great article. Thanks!

  7. Great article, glad I have read this as I’m off to the aquatic centre and now at least I know what to look for, thanks

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