Sand Stirrers and Detritivores in Reef Aquaria by Kenneth WingerterThese days, a pretty good number of aquarists (a majority of them, perhaps) prefer bare-bottom tanks. Bare, as in, no sand or gravel on the tank floor. Just as these folks opt for bare-bottom display tanks, they opt for bare-bottom refugia. The basis of this trend is a fear of detritus–specifically, that substrates attract and accumulate detritus. Now, detritus does kind of suck, as it looks gross and stores nutrients that can (as they are released) contribute to unwanted algal growth. At least in theory, if you don’t have a substrate, particulate organic matter cannot easily get trapped on the bottom, and so your tank will be cleaner. This all deserves a closer look. And some deeper thought. Sand Stirrers and the limits of mechanical filtration In bare-bottom tanks, just as in tanks with a substrate, detritus is eventually mineralized (broken down) into excess nutrients and dissolved organic waste. “No problem,” the bare-bottom proponent might say, “I’ll just go heavy on the mechanical filtration.” Fair enough, so long as mechanical filter media are thoroughly rinsed on a regular basis (i.e. daily), very little of entrapped particulate organics can mineralize much. Effective means of nutrient export, right? Yes and no. Consider first of all that mechanical filtration is indiscriminate. It removes all particles down to some particular size–both bad and good. This means that in addition to all that rinsing, you’ll also have to mess with it (i.e. remove it or somehow divert flow around it) whenever you feed. Otherwise, all of those pricey fish foods and coral foods you add will almost instantly become “waste.” Top-dollar detritus. But an even bigger concern about aggressive mechanical filtration is pod mortality. Think about it… A coarse mechanical filter medium that cannot strain particles of less than, say, 75 microns is pretty much worthless. Yet, finer media that strain anything smaller than 75 microns will remove most adult copepods and even many copepod nauplii. They’ll be harder yet on larger pods like amphipods. No, we’re not saying that mechanical filtration outright decimates an entire pod population. Nor do we claim that pods simple perish upon first contact with a mechanical filter medium. What we are saying is that fine mechanical filtration does trap some (and potentially a lot of) pods and therefore limits their population size. Really “good” mechanical filters can completely eliminate copepod species that undergo a pelagic adult life stage. See the vicious circle here? You keep a bare-bottom tank to enhance the collection of detritus in your mechanical filter, which you install because you have a bare-bottom tank–to the detriment of copepods, which are your best weapon against detritus in the first place! At this point, we present an alternative (and dare we say more natural?) approach; keeping a substrate, using only super-coarse mechanical filtration (if any) and promoting the degradation of detritus by detritivores such as (but not limited to) copepods. The hitch? You need a crew of so-called sand-stirring organisms. Stirrers accomplish two important tasks. Firstly, their excavations encourage the release of organic matter from deep within the substrate. These wastes are otherwise inaccessible to detritivorous animals not just because of layer of sand above them, but also because they may be situated in anoxic areas. This leads to the second job, which is aerating the substrate surface, thereby increasing the depth at which aerobic detritivores can safely forage. Substrates=Reef food factories There is a very large diversity of detritivorous reef critters. As one might expect, many of these sediment-dwellers are tiny. The little guys include microcrustaceans such as harpacticoid copepods, cerith snails, various worms, etc. There are many larger detritivores as well. These range from sand-sifting gobies to sand-sifting sea cucumbers. It almost all of these cases, the creatures are not really eating the detritus to eat the detritus; rather, they are going after the rich microfauna that is associated with the detritus (bacteria, fungi, protozoa, etc.). The smallest detritivores just crawl around within the sand and gobble up teeny particles as they find them. Larger ones, however, swallow up big mouthfuls of sand, detritus and all. They then either strain out the goodies and spit the sand back out, or they actually eat the sand, digest the goodies, and then poop the sand. The evidence of this latter group is sometimes observed over the sand bed surface every morning in the form of distinct formed, clean, white sandy pellets. Not all sand stirrers are detritivores and not all detritivores are sand stirrers. For example, certain fish (e.g. jawfish) and certain shrimp (e.g. pistol shrimp) build elaborate borrows. These burrows help aerate deeper parts of the sand bed through irrigation (that is, movement and exchange of waters between the top and bottom portions of the burrow). This allows other creatures (especially detritivores) to forage deeper in the immediate area, and so compliments and promotes the activities of sand stirrers. Some creatures help to keep the sand bed clean even without doing any stirring. These range from pods to detritivorous fish (e.g. court jester blennies). The reason is pretty simple: Where detritus is consumed at the substrate surface, less detritus can settle deep within the substrate. Basically, having a large and diverse clean-up crew and a diverse team of sand stirrers can significantly reduce the need for mechanical filtration, if not eliminate the need altogether. Some creatures will fill just one of these roles, and others will fill both. What’s important is that the aquarist assembles an ecological community that breaks down detritus as quickly and thoroughly as possible–the widest size particle range, the most types, in all locations of the system. This encourages rapid recycling, which encourages large populations of both zooplankton and bacterioplankton, which are both important components of the coral diet.
ryorzins says January 31, 2022 at 1:05 pm I would get a diamond goby but my substrate is CaribSea Hawaiian, black. It is not a fine powdery sand. Not sure if the diamond goby can handle sifting my sand. Reply
billy.t.williams12 says February 28, 2022 at 2:21 pm That is sad to hear, Diamond Gobies are some of my favorite fish. Sounds like you need a new tank and new sand! lol Reply
Raven says March 3, 2022 at 7:18 pm would loaches be part of the fish you would not use subratie with and nice article Reply
ernie.alvarez0325 says May 30, 2022 at 4:44 pm I love My diamond goby! Always digging up the sand and keeping the bottom clean! Reply
JohnR says August 8, 2024 at 8:00 am Years back I tried a sandless tank and I noticed that my fish were not free swimming lime some of my other tanks. After a few months, I added sand to it and the next day everyone was happy swimming about. Only thing I can think of is that they were seeing an obis below them and were staying in the rocks for safety. I keep a good mix of stirrer in my tank now. Yes, they do like to pile the sand in different locations throughout the tank, and I have to redistribute when I clean it on the weekends, but it keeps things interesting. Reply
Samantha Obergas says October 14, 2024 at 4:03 pm Thank you for sharing your experience—it’s always interesting to hear how different setups impact fish behavior! Your observation about the fish being less active in a sandless tank is really intriguing. It’s possible that the absence of a sandy substrate created a visual effect that made the fish feel more vulnerable, as you mentioned. Fish often use visual cues from their environment for comfort and safety, so adding sand likely gave them that sense of security they were missing. I’m glad to hear you now have a good mix of sand stirrers in your current tank. As you noted, they do tend to pile the sand in certain areas, which is all part of their natural behavior, but it’s great that you’re keeping them happy and engaged in their environment. It can certainly keep things dynamic and, as you pointed out, adds some variety to your routine when maintaining the tank. Thanks again for the comment, and happy reefing! Reply
James A Cabeceiras says June 7, 2022 at 9:02 am Hello, my daughter’s reef tank has the same Hawaiian black and it does have a lot of powdery dust in it. What I did was put a bristle worm trap in my tank and caught about 30 worms to sift her sand and they are doing a great job along with our watchman gobies! Reply
crplcarott says June 8, 2022 at 12:20 pm I had a Diamond goby and the same substrate. It handled it with no problem. Just make sure you have a good top on your aquarium because they are escape artists. Reply
crplcarott says June 8, 2022 at 12:20 pm I had a Diamond goby and the same substrate. It handled it with no problem. Just make sure you have a good top on your aquarium because they are escape artists. Reply
Fawn Curtis says March 25, 2023 at 10:03 pm Try Tongan sand sifting snails. They are striking for sand sifters and do a great job. Reply
dgbsmb says April 16, 2022 at 9:29 am I love my Diamond goby, he sifts my sand from one to the other of my 300 gallon reef tank, constantly turning my sand Reply
Ricks Garage says January 31, 2022 at 2:04 pm I love the little critters that live in the sanded and come out at night Reply
Jimmy Kok says June 19, 2022 at 10:46 pm sand provides a good home for many beneficial creatures Reply
Botzz28 says January 31, 2022 at 2:53 pm Now that I am populating my tank with eco pods can I keep the more hard to keep starfish other than a regular sand sifting star ? Reply
Brian Veach says January 31, 2022 at 2:59 pm I’ve seen such an improvement in my tank when I focused on keeping the sand clean. We’ve added starfish, crabs, snails, hermits, and sifting fish all with the intention of improving our sand. When we did that, the coral exploded! The benefits have been clear. Reply
tonymutti says January 31, 2022 at 2:59 pm Gobies and snails like Cerith are great. I generally stay away from sand sifting stars because they each a lot of the microfauna. Reply
Eric says February 26, 2022 at 6:45 pm I’ve always had some type of ? stirring or sifting creature in my tanks since 2004. My by far favorite is a pistol shrimp with a Goby, no matter the species! Reply
sfinnell says April 16, 2022 at 7:57 am I love my pistol shrimp sharing its home with my goby pair, but the bigger that he grows, the more sand that he constantly moves. He collects it near and far in my tank and as a result disturbs a lot of corals and rock with his never-ending construction. Now, I don’t know if I love him so much! He definitely cleans the sand!! Reply
Eric says February 26, 2022 at 6:45 pm I’ve always had some type of ? stirring or sifting creature in my tanks since 2004. My by far favorite is a pistol shrimp with a Goby, no matter the species! Reply
Ed says January 31, 2022 at 3:57 pm Need more cleaner crew since my Dracula goby jumped into the overflow and past the UV sterilizer. Reply
debken890 says February 1, 2022 at 8:42 pm Great post. Love my CUC including diamond goby always cleaning sand. Would never go bare bottom doesn’t look natural Reply
Leroy Lewis says November 22, 2023 at 1:57 pm If you have sand in your aquarium it is easy to find something you like to watch. Reply
Alex Merida says February 1, 2022 at 12:51 am I have a pink spotted goby and some nassarius snails. Thanks for the awesome information #Algaebarn Reply
cmykredesign says February 3, 2022 at 9:48 am I use to have a Tiger jaw fish he used little shells to make his house and would throw crabs who got inside his house Reply
vegasv128 says February 6, 2022 at 2:04 pm I don’t think sand gobies like my chunky black sand. Reply
Cassondra Cunningham says February 7, 2022 at 3:12 pm My goby creates valleys and mountains all in my tank with the sand. Reply
chief300 says February 7, 2022 at 3:32 pm I like sand shifters, but I can’t seem to keep them alive. Reply
robncasey says February 8, 2022 at 11:39 am Glad we have a new order of pods from Algae Barn! Can’t wait for them to arrive! ♥ Reply
tbrown3589 says February 8, 2022 at 6:48 pm My Hector’s stirs some, but I definitely need another. I’m thinking a couple of conches. Reply
alenm826 says February 10, 2022 at 5:17 pm What better then to see a sandy snow shower in your tank daily gotta love the goby. Reply
James Bradshaw says February 14, 2022 at 3:27 pm I’ve always been a fan of sand so conches are an absolute must for me. Besides being an abnormal creature in my tank that gets oohs and ahhs from guests but they are the best sand stirrers I’ve ever had. With the combination of monthly subscriptions of pods from algae barn, my water changes are every few months max. Reply
gerrynator4 says February 14, 2022 at 11:39 pm I have a tiger sand conch, he’s great at sand-sifting, and is funny looking Reply
gerrynator4 says February 14, 2022 at 11:39 pm I have a tiger sand conch, he’s great at sand-sifting, and is funny looking Reply
Beth S says February 15, 2022 at 11:54 am My favorite was my horseshoe crab. Fun to see when he periodically resurfaces Reply
Robert Benedict says February 21, 2022 at 4:53 pm That is a great article. I am always adding new and different things to my tank to help keep it clean. Reply
rabenedict2 says February 21, 2022 at 4:57 pm Great article. I am always adding new detritivores to my tank to help keep it clean! Reply
Alan Biddle says February 21, 2022 at 5:12 pm I have been thinking of trying running without mechanical filtration. Helpful article. Reply
danielstrahan.11 says February 21, 2022 at 8:51 pm A variety of sand sifters is a must in all my tanks Reply
jason_lifted35 says February 26, 2022 at 10:53 am Need to get a tiger sand conch, love my diamond watchman goby. Reply
Jacob Carpenter says February 27, 2022 at 5:57 pm They remind me of the fish from SpongeBob with the pizza Reply
Jeff Carr says March 8, 2022 at 5:34 am Gobies are good, but I have a nano so adding another fish won’t help much. I think I will focus on other CUC types like… pods! Reply
Jeff Carr says March 8, 2022 at 5:34 am Gobies are good, but I have a nano so adding another fish won’t help much. I think I will focus on other CUC types like… pods! Reply
tkshaffer70 says April 4, 2022 at 12:54 pm Cannot say enough about the yellow-headed sand goby. In my experience they will eat any and every prepared food provided and still spend all day turning over the sand bed. Very attractive as well. Just be aware they will climb up in the water column as expelling the sand. Nice article…very informative! Reply
patscheuplein says April 4, 2022 at 6:23 pm I have 2 harbour gobies. They sift sand so much that I have move it back. Reply
Brad Martin says April 11, 2022 at 3:29 pm I got some pods and am looking to get a goby to help ster sand around. Reply
Brad Martin says April 11, 2022 at 3:29 pm I got some pods and am looking to get a goby to help ster sand around. Reply
Brad Martin says April 11, 2022 at 3:29 pm I got some pods and am looking to get a goby to help ster sand around. Reply
Brad Martin says April 11, 2022 at 3:29 pm I got some pods and am looking to get a goby to help ster sand around. Reply
sarah.sandpoint says April 11, 2022 at 8:34 pm I wonder if I could get some sand sifting gobies when we have a pretty established blenny, he seems okay with all the other fishes – would love to add some gobies, they are pretty cool! Reply
blackadonai says April 14, 2022 at 8:58 am I already have a diamond goby. He sure moves a lot of sand around. Unfortunately I’m having a cyano outbreak and he won’t touch any of the sand with cyano on it. I also have a sand conch and a tiger tail cucumber that I only see occasionally. I’d also really like to get a couple of those court jester blennies Reply
mariahdavila says April 16, 2022 at 9:07 pm Great blog wonderful info. I’ve been trying to get my little paws on a diamond goby. One day! Reply
Brandon says April 18, 2022 at 4:15 pm I’ve always loved having a diamond goby. It’s so fun to watch them gobble sand. Such a cool fish. I need to upgrade my nano so I can have one again. Reply
Will says April 22, 2022 at 11:09 am Gobies are good, except I’ve had bad luck with them jumping out of the tank.. Reply
shawntolman13 says April 29, 2022 at 9:57 pm I am just setting up a 155g with DSB.. definitely have the sand stirrers! Reply
ernie.alvarez0325 says May 30, 2022 at 4:50 pm Love my diamond goby. Keeps sand nice and clean! Reply
Dan Russell Zabler says June 6, 2022 at 2:12 pm Never had a diamond goby but I had a watchman goby with a piston shrimp. They always kept my sand nice and white. Reply
markwdunlap88 says June 6, 2022 at 2:58 pm I loved my goby until he became daring and decided to go skydiving during feeding time… didn’t catch him in time. Haven’t tried another yet Reply
schmidtcaters says June 10, 2022 at 7:05 am One of my constant struggles is keeping enough. And maybe the right balance of sand stirrers in the tank. Keeping pods alive is a huge focus for me as I have a dragonette. Reply
Andrea says June 14, 2022 at 5:43 am My diamond goby remodels my tank allll the time! Also, if I put a coral on the sand bed, he often says nope and moves it – usually hidden where it is hard to find it. He is a funny little guy, but he keeps my sand very clean…. with lots of mountains. Reply
sclarke_o says June 16, 2022 at 5:55 am I want a jaw fish but I currently run bare bottom … I’m going to switch I just don’t know when ….. sand stirrers are fun to watch seen them in the wild on a dive!!! Reply
tcobosco says June 21, 2022 at 3:55 am My black and white Clowns do a great job keeping their acre on the reef very stirred up lol Reply
Alan J. Tomasetti says July 8, 2022 at 4:59 pm I’d love to have one, though hopefully it doesn’t burry the corals in the sand too much! Reply
kingmahen says October 29, 2022 at 9:15 am I can’t have any Gobies because they would bury my sand Ed corals like my Scolys, Trachy’s and Lobos Reply
kingmahen says October 29, 2022 at 9:15 am I can’t have any Gobies because they would bury my sand Ed corals like my Scolys, Trachy’s and Lobos Reply
Austin Clark says November 3, 2022 at 3:59 pm Looking forward to adding my diamond goby. Just making sure he will have enough copepods to be big and healthy. Reply
Kelly Davis says November 3, 2022 at 10:50 pm I love my pink spotted watchman goby! They don’t usually sift but mine does. Also tries to be an escape artist when given the chance. Reply
KiltedReefer says November 5, 2022 at 2:39 pm Someday I hope to get my diamond goby and have him create his mess in the sand. Need to increase copepod levels first. Reply
Kass says November 14, 2022 at 8:07 pm Ready to get my tank started and add some of these little work horses. Reply
eric says November 24, 2022 at 9:12 am Heard sand stars actually harm your substrate by taking away all the beneficial stuff Reply
jackbauer24.1 says November 27, 2022 at 10:28 am Why haven’t there been any winners since the first of October ? Reply
Andrew says December 20, 2022 at 12:51 pm I would love a sand sifting sea star, but with my tank only 6 months old I don’t want to risk him starving to death. Reply
chriscatherman says December 20, 2022 at 1:18 pm I have a Diamond goby & a conch they keep my sand bed looking beautiful!!! Reply
Marijane Stevens says December 23, 2022 at 8:24 am It doesn’t feel like a reef tank unless you have a sea star. 🙂 Reply
Carlos Matias-Tejada says March 9, 2023 at 4:22 pm me too. until it ran out of food and melted on me. i would target feed it and nothing!! Reply
Kelly Pinckard-Hazzard says February 8, 2023 at 4:28 pm Love the sand sifting stars and love your articles! Reply
globalfisher says February 27, 2023 at 1:46 pm Great post! I have had a few gobies before and really enjoyed them. Reply
Jeremy says March 3, 2023 at 10:05 am I have a yellow watchman with a pistol shrimp, but she’s not the most active. Reply
Barry Roper says March 16, 2023 at 11:57 am Looks like a sand-sifting gobie may be my next purchase… Reply
Noah Fowler says April 11, 2023 at 3:00 pm The sand is a whole different world I bought a microscope to see all the microscopic live living there. It’s amazing Reply
janelle says July 26, 2023 at 4:39 pm I heard sand sifting starfish can annihilate the organisms in the sand in an incredibly short amount of time Reply
RYAN LEE SMITH says August 28, 2023 at 11:26 am always a good read, far to many of us underestimate our sand beds. Reply
Nicholas Aguiar says September 13, 2023 at 4:58 pm interesting starfish, it blends well with the tank but not too colorful to take away from the centerpieces, especially in small tanks. i’d definitely get one for my current tank. Reply
Jeffrey Miller says October 22, 2023 at 7:09 pm Always liked a sand bed and I will probably always stick to it. Reply
professorcanswanky says November 12, 2023 at 9:34 am I’ve got a diamond watchman and two tiger conchs in my 57 gallon and they keep my sand bed spotless! Reply
Noah Fowler says November 19, 2023 at 7:07 pm Very underrated live stock for your tank I always have multiple species that will move thru the sand Reply
Amber Breedlove says December 1, 2023 at 7:06 am I CANNOT WAIT until i get more little critters in my tank 😍😍😍 Reply
Brendan says December 5, 2023 at 5:26 pm I have a diamond goby, and I could see the impact he had on the sand bad quite quickly. Reply
Matthew Hubble says March 21, 2024 at 7:39 pm I have two gold headed sleeper gobies and they are amazing at sand sifting…. And spitting sand all. Over the rocks lol they also have their home came decorated with empty shells haha Reply
Joseph Uttlinger says July 10, 2024 at 9:15 pm Don’t have a sand sifter yet, but it’s definitely on my list. Reply
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