One thing you don’t want to overlook for every reef tank is the little critters, the "janitors" or clean-up crew, to help keep your tank in shape. These little creatures help control nuisance algae, remove detritus, eliminate the occasional small dead fish trapped beneath the rockwork, scavenge for any scraps of food that fall to the bottom or in between the rocks, among other things. In this article, we’ll discuss some of your options on what is available for the reefkeeper to help reduce the maintenance of the tank, and do it naturally, without having to resort to chemicals.

When you first mention snails, most freshwater aquarists cringe as they think of uncontrolled populations of these creatures munching on their prized plants, clogging the filters, cluttering the glass, and literally taking over the tank. But for saltwater, these creatures are not only good for the tank, they are a necessity for helping to reduce the nuisance algae. Now, there are predatory snails that eat clams and other corals, but we are only interested in the herbivores that will help control the algae that eventually will grow in your reef tank.

Astraea tecta snails fit the bill nicely, due to their relatively small size, which is about 1-1 ½ inches. They are cone shaped, and because of their shape, they sometimes will fall and get stuck upside-down, when you will need to help them back on their "foot". Otherwise, they may fall prey to other scavengers. You will find that "bigger" in a reef tank is not always "better". These snails are slow moving, eat large amounts of algae on the glass and rocks, and cannot knock over or move but the smallest corals from their perch, versus the much larger Turban (turbos) snails, which can get as big as three times the size of an Astraea snail. Turbo snails also are known to bulldoze their way across the rocks, dislodging anything that gets in their way, other than the rocks themselves. Generally, you will find the snails are busy eating the algae off the glass when you first check the tank early in the morning. They tend to resort to the rocks and bottom layers of the tank during the peak lighting periods. You’ll see their zigzagging trails along the glass if you haven’t cleaned it off in a while. Astraea snails have been known to reproduce in the tank, but I have never known this to be a problem, but a blessing instead. Your local fish store would be glad to take any extras, as these beneficial snails generally sell for up to $2.99 a piece. Unfortunately, these snails don’t live forever, and you will probably need to replace them periodically, if they don’t reproduce enough in your tank, at about 1 snail for every 2-3 gallons.

Another good candidate is the blue-legged hermit crab Clibanarius tricolor. This little critter is worth his weight in gold, and was the last resort that saved my tank during a hair algae explosion that occurred the second year of my reef tank when I was doing a lot of traveling and did not stay on top of the maintenance. I nearly lost all my corals, as this nuisance algae literally smothered them. All the rock scrubbing was in vain, as when I returned from my trips, so had the algae. I loaded up the tank with approximately one crab per gallon, and every time I came back from a trip, you could see the algae disappearing, until after about three months, it was totally gone. These crabs not only eat the hair algae on the rocks, unlike the snails, they will pick the algae off the coral skeletons without stressing the corals. I was amazed at how fast they worked, around the clock, at removing the nuisance algae. They can get into the tightest areas, such as between the rocks and in the corners, to do their job, and do it well. And when the algae is gone, they will resort to scavenge the tank for leftover food on the bottom and in between the rocks. They are also very efficient at cleaning up dying coral tissue, or other dead animals in the tank. This is not a recommendation to keep anything dying or dead in the tank that you observe, but it can prevent a catastrophe on something you may miss, or is under the rockwork. I have left a smaller dying hard coral in the tank as they will clean it up within a day. They only live for about two years, so you will need to replenish them from time to time, at about 1 crab for every 2 gallons. They do have a tendency to attack the Astraea snails, if they "fall and can’t get up", and have an appetite for baby snails, so you have to keep an eye out for them.

One of the prettier scavengers is the skunk cleaner shrimp Lysmata grabhami. With their bright red backs with a white stripe down the middle, these critters tend to be active and out in plain view during the day, although they are much more active at night scavenging for food. They are fun to watch, especially when a fish decides to let them pick at, or "clean", their bodies for parasites. They are quick and can dart for a morsel of food, then run off to a private spot to eat. Occasionally, they will steal a morsel of food from slower eating animals, such as starfish. Again, you can keep several of these shrimp in the same tank, and they will generally be seen hanging out together on the rocks. They can reach a length of 3-4 inches and have a lifespan of about three to four years.

One of the largest scavengers that is safe for a reef tank is the brittle starfish, or "serpent stars" Ophiuroids. They are available in several colors, including red, yellow, orange, and the most common, green, and can live for years in your reef tank. All are excellent scavengers and have the ability to get their tentacles in the tightest spots, such as in between and underneath rocks, to get at any trapped food. Their food includes leftover fish food, fish feces and any dead organisms. They do not have eyes, but can "sense" the food the minute it gets into the water. It is fun to watch them scurry out from their hiding places after you start feeding the fish, hoping to grab a morsel or two. I currently have two in the 125 gallon, one red one, and a green one I have had since I started the tank eight years ago. My green serpent star has reached a length of 24 inches, tip to tip, and makes quite an entrance out to the front of the tank, when he is hungry. I do have to feed him, due to his size, with frozen krill and crabmeat. He’ll grab a piece that I hold near him with tweezers and roll it up to his mouth in a matter of seconds. My only problem is I have to feed each of my cleaner shrimp with a morsel first or they will try to pry the food away from the starfish. The six-line wrasse and Clark’s anemonefish in my tank will also try to steal some food from this slower eating animal.