When looking for an aquarium cleaner, the Emerald Crab is one of the best sea animals to shop for. Considered a superb algae eater, this crab is also well known for eating up any remnants after feeding the tank fish.

Appearance of Emerald Crab

The emerald crab is named after its colorful yet distinct appearance. The overall body color is a shiny emerald green. It is a few inches in diameter (1.5-2inches) and has hairy legs punctuated with powerful claws. The body is almost flat. A quick glance would give one the impression that it is the bubble algae. On the contrary, the later is a favorite delicacy of the emerald crab.

Habitat

The crab is an original inhabitant of the Caribbean Sea, with some found in The Gulf of Mexico. Notoriously known for clearing an algae formation, this sea animal is a darling after fish have fed. Most hobbyists who have issues with cleaning up a tank after fish have had their meal are likely to find it an ideal choice. It literally cleans the tank and one may not be obliged to clear any leftovers that are likely to make the aquarium smelly.

In its native habitat, Mithraculus Sculptus, as it is scientifically referred to, is known to be nocturnal. At daytime it prefers to hide in caves and crevices. It comes out at night to scavenge for leftovers and grab any algae it is likely to chance upon. When it gets used to a tank however, it may outlive its shyness and come out of its hiding during the day.

Tank Requirements

Being a tank cleaner with minimal special needs, it often survives most tank conditions. However, the following conditions may make its existence more comfortable.

A small sized animal like the emerald crab will survive in a big, medium or small tank. Naturally, it is a cleaner that is stocked with other fish. Disclaimer though; there are some fish that are likely to gobble it up and these should not share a tank with it.

Temperatures of about 75-80 Fahrenheit would be very ideal. A pH of 8.4- 8.4. Calcium 420-440 PPM, Magnesium of 1260-1350, Alkaline of 8-9.5 DKH, Nitrates below 10 PPM, Phosphates below 10 PPM . The water chemistry may be raised gradually as it helps create ideal conditions for algae growth. When phosphate levels go up to 10, it is time to make a water change.

Provide live rock so that they find a suitable condition for them to forage into. As a way of ensuring the environment remains friendly to it, dosing pumps may be provided. This will ensure the levels of dosing in the tank are kept constant. Of course some hobbyists do this manually but it is hectic. The pump makes this work easier. Sand and gravel are another necessary addition to fulfill all the tank requirements.

Feeding

Crabs are by nature scavengers that feed on leftovers. They eat anything from meaty foods to bubble algae in the aquarium. They also enjoy leafy foods. To get rid of algae formation in the aquarium, emerald crab will be of great service. Other foods to help supplement its diet include:

• Live micro algae
• Nori or sea-weed could also be a delicious dish to the crab
• Mysis shrimp is another delicacy that can be added to its diet
• Formula one fish pellets. Small ones for a start. They are kept in nitrogen bags. This ensures they are soft and easy to digest. If garlic is added to them, the crabs are able to be disease resistant.
• Krill could be added to the diet too. It enhances the green shiny color.
• Spirulina and plankton could be added as well.

Most hobbyists assume that since the crab is a cleaner, it does not need a special diet. This is not so. Apart from the remnants after the other tank-mates have fed, supplement diet is a necessity. This way, the crab does not seriously interfere with the corals. As a matter of fact, the crab has an affinity for small fish. When keeping it with tank-mates, do not keep the very tiny fish with it. The powerful claws can disrupt the body make-up of most types of fish.

Other important information for a hobbyist:

One crab is enough to take care of a tank. There is no need to stock many of them in a single tank. As much as they feed on algae, a big formation of it may not be eaten up successfully. In case there is a huge build up, it will call for manual removal and setting right water conditions that will not favor lots of algae growth.

Crabs shed off their exoskeleton as they age. Once the outer skin is shed off, the remnant is a picture of the real crab. One may think the crab is dead while it will be hiding under rocks or crevices in the tank. It is important to remove whatever is left behind as it may prevent the build-up of nutrients in the aquarium. Remember they are scavengers and will gladly feed on the dead fish as well. This should not appear strange to a first time hobbyist.

Larger fish find them delicious and may pry on them. When selecting tank-mates, be sure only small friendly ones are in the tank. When kept with other fish, keep a close eye on the tank because they may attempt to claw away part of some fish. While they often attack fish when hungry, there are times when supervising their movements around other fish for a few weeks is necessary.

Breeding

Not much is recorded about breeding the emerald crab in captivity, but there are always first times. Differentiating males from females is difficult. When planning to spawn them, collecting a variety of the crabs and placing them in the same tank can create an opportunity for breeding.

Some hobbyists have reported observing two crabs locked in something like a tight embrace. This means that even in captivity, there is a likelihood of mating.

Emerald crabs are a necessity for keeping the tank clean. Taking care of them can be a beautiful experience because they have simple needs.

The animal kingdom is full of rare and fascinating species. Among some of the most amazing underwater animals include the different types of cleaner shrimp. Perhaps the most interesting fact about this sea animal is that it can dance. It also clears parasites from other fish mouths. It enters into the mouth of a fish, gets a parasite and bounces out without the fear of getting gobbled up by a fish or eel!

Like a number of other sea animals, the shrimp has a truly unique coloring. The orange color is evenly spread along its sides. A long red stripe, like a red ribbon is stretched on the dorsal side and is then bisected by a white almost narrow band. The shrimp has three thin yet long antennas on the head. On the tail are white tiny spots.

Shrimps are classified as crustaceans. They belong to the Hippolytidae family, in the genus of Lysmata amboinensis. They come in a number of varieties that would interest an aquarist.

Types of Cleaner Shrimp

Lysmata Cleaner Shrimp

The Lysmata amboinensis and Lysmata grabhami are the most common aquarium shrimps. They are also a strange variety as they literally clean most types of debris and parasites from fish. It is not unusual to find a large fish open up its mouth and a shrimp gets into it to eat away parasites stuck therein. For a first-timer, it may be scary as one imagines the shrimp will be gobbled up. Well, it gets even more interesting when fish come to the shrimp to be literally cleaned up.

Popular belief is that the shrimp’s white and red strips protect it from predators in the form of other larger fish and eels. The truth however, is that the color is not protective enough.

Camelback Shrimps

This shrimp obtained its name from a small hump found on its back, like that of a camel. A number of these Rhynchocienetes species are mostly found in tropical seas around the world. When harnessed in tanks, they easily become proficient cleaners, making them a very desirable lot.

They are very attractive as they exhibit extremely vibrant colors. Their cherry-red colors with contrasting white stripes and dots make them quite attractive. One great factor worth remembering is that different types of cleaner shrimp often eat coral reefs and may deplete a reef stock.

Harlequin Shrimp

With a lovely name, this rather shy yet mild tempered shrimp is not only delicate but sensitive as well. It likes to hide behind coral substrates or hard rock owing to its timid nature. At daytime, it rarely comes out from its hiding place, preferring to stay hidden under coral reefs. Mealtimes are usually during the night when they move in pairs. The female is slightly larger than the male.

Like the rest of the cleaner shrimps, the harlequin has lovely colors too. The body is largely white with large black dots.

Fire Shrimp

Scientifically referred to as Lytmasa Debelius, this extremely beautiful shrimp is rather difficult to see owing to its nocturnal nature. It exhibits a bright red body with white speckles dominant on its head. It has a number of scarlet red legs that are easily distinguishable from the antennae that are long and white. It often hides behind coral especially if the tank is well lit most of the time. They love to feed on polyps and may be a poor choice for a shrimp lover.

Peppermint Shrimp

Its scientific name is Lysmata Wurdemanni. Originally from the Caribbean, this shrimp is quite reclusive. Once introduced into a tank, it enjoys staying out of sight, making it difficult to be seen. It feeds on small polyps and as a result, may destroy the mini-reef considerably. It also eats aiptasia anemones that may interfere with an aquarium.

The peppermint shrimp may easily confuse one with its eastern pacific counterpart, Lysmata California. However, at normal reef temperatures, it may not survive for long. It is therefore necessary to check on this for an extended lifespan.

Banded Coral Shrimp

In an aquarium, the Stenopus Hispidus is known to get along well with most kinds of fish. Yet it has enemies too! Trigger fish and eels love to feed on it. When presented with parasites, it actively cleans fish.

Mantis Shrimp

Popularly known as Odontodactylus Scyllarus, this sea animal is very beautiful. They come in two hunting categories namely, smashers and spearers. Smashers are very forceful. With their club-like claws, they easily pulverize their hard shelled prey into a sumptuous meal. Snails are their most favorite clients. On the other hand, spearers silently claw their soft- tissued prey into meals. Their claws are spear-like.

Facts about the cleaner shrimp

Different types of cleaner shrimp are quite popular and are a necessity in an aquarium as they help clean it up. Other than that, they also groom fish in a given tank. Facts to remember about the cleaner shrimp are:

• It has two long antennae found on its head.
• It has five long legs. Three of these are for walking and are called pareiopods. The other two are for swimming and are referred to as pleopods.
• They often set up a cleaning station where fish in need of cleaning come for sprucing up. The cleaner shrimp crawls on a fish body, clearing it of any debris and parasites. It even gets into its mouth without the fear of getting gobbled up.
• It feeds on algae and parasites. At times it feeds on snails and zooplanktons.
• A female shrimp may lay anywhere from 50,000 to one million eggs at one given moment.
• Baby shrimps, known as nauplii hatch out of eggs within 24 hours. They then feed on reserves of the yolk found on eggs that are not hatched.
• During the mating season, the shrimps eat their own. This is known as cannibalism.
• After fertilizing the eggs, the males feed on the females.
• Some shrimps are born with both male and female organs. They are referred to as hermaphrodites. This characteristic is common among the scarlet shrimps.
• Shrimps are mainly predated upon by lionfish, Moray eels, trigger fish and cat sharks.
• Young shrimps are hard to care for as they are difficult to feed. This often leads to a high mortality rate during their earlier stages.
• Despite the difficulty in breeding shrimps, they are sold at the market.
• The shrimp’s heart is believed to be in the head.

 
If you’ve ever had a reef aquarium, then you’ve almost certainly purchased a snail or two to control nuisance algal growth. But which one to get? The possibilities are endless… Turbo or Tectus or Trochus or Tegula?! But a new study is out to lend a little scientific clarity to all the aquarium anecdote. Writing in the journal PLoS One, researchers set up experimental aquaria for three commonly exported species, sold to them under the names Turbo fluctuosa, Astraea tecta, and Margarites pupillus. Twenty specimens of each were acquired through aquarium suppliers, but, remarkably, none of these identifications turned out to be correct. Specimens sold as the Mexican Turban Snail (Turbo fluctuosus) were instead the Zebra Turbo Snail (T. bruneus), a widespread Indo-Pacific species. The Fenestrate Top Snail (Tectus fenestratus), another Pacific species, was sent in place of the Caribbean’s West Indian Starsnail—aquarists will usually see that one identified as Astraea tecta, but the valid taxonomy is actually Lithopoma tectum. And, lastly, the Margarita Snail (Margarites pupillus), a temperate species known from the Bering Sea (!!!) to Southern California, was in actuality the Western Banded Tegula (Tegula eiseni), which has a warmer range in the Eastern Pacific, from Central California to the Baja Peninsula (presumably from where specimens are sourced). Now, I just want to point out here that a surprising number of people involved in the aquarium industry regard this sort of nomenclatural nitpicking as pompous and unnecessary, but, as we’ll see, the survival rates of these species can be drastically different from one another, as is their efficiency at grazing upon algae, along with perhaps the preferences they might have in choosing their algal diet. How are we to know if one snail is a better choice in comparison to another when they are sold so interchangeably? 

 
And as an example of these stark differences, of the twenty Turbo snails used in this experiment, every specimen survived, while just 10% of the Tegula snails made it to the end of the 53-day study. Tectus fell somewhere in the middle, with 13/20 making it to the end, with most of the mortalities happening within the first month. It’s a shame that there isn’t more data like this available, as it would go a long way towards informing the purchasing decisions of aquarists. Nothing is more frustrating than a tank full of dead snails. I’ll take this opportunity to give my own two cents on the subject. Tegula snails don’t seem designed for the warm waters of a tropical aquarium and should probably be avoided. “Astraea Snails” are also a questionable choice, with perhaps half of all collected specimens dying before they’re ever purchased, and the other half eventually flipping onto their backs to suffer an ignoble death. To be fair, those that do survive are good at their algae-eating job, but this initial mortality rate and minuscule long-term survivorship is just abhorrent. In my experience, having dealt with countless thousands of aquarium gastropods, Turbo snails are the clear winner here, with most acclimating well to captivity, provided they’ve been shipped appropriately. If there is any drawback to the Turbo snail, it’s their seemingly malicious desire to topple unsecured corals, but it’s not really fair to blame them for that. Along with their bulk comes an unrivaled appetite for the algal menace. This study also examined the rate at which these three snails consumed algae (in this case, a puree of Ulva Sea Lettuce dried onto a plate). By quantifying the amount eaten after a 24-hour period, it was found that Turbo is twice as effective as either Tegula or Tectus. It’s a shame there weren’t more snail species examined here. It’d be great to know how the true “Astraea Snail” (i.e. Lithopoma tectum) compares, since it’s probably the most frequently sold snail in the US. The Banded Trochus Snail is another species worth investigating, since (at least in my experience) it seems to have a higher survival rate than most. And what about some of the other herbivorous snail families seen in the aquarium trade: Cerithium, Cypraea, Strombus, Columbella, Haliotis, Nerite, Norrisia. Which of these is worth a damn, and, most importantly, which are best at controlling Derbesia and Bryopsis and all the other nuisance algal species? 

   

• Watson G, Davies J, Wood H, Cocks A (2018) A comparison of survivourship and function (grazing and behaviour) of three gastropod species used as clean-up crew for the marine aquarium trade. PLoS ONE 13(6): e0199516. https://doi.org/10.1371/journal.pone.0199516

Joe is classically trained in the zoological arts and sciences, with a particular focus on the esoterica of invertebrate taxonomy and evolution. He’s written for several aquarium publications and for many years lorded over the marinelife at Chicago’s venerable Old Town Aquarium. He currently studies prairie insect ecology at the Field Museum of Natural History and fish phylogenetics at the University of Chicago.

Ever wondered what an underwater centipede looks like? Well go no further, here we have the Bristle Worm. They are worms that come from the Polychaete family, they are segmented worms and they love to spend their life in the dark. Yes, they are nocturnal creatures.

Bristle worms can be found in salt water aquariums and there are mixed claims about them. Some people claim they are good for the aquarium ecosystem because they tend to eat food that fish leave behind and they clean the aquarium just like an algae-eater, but some people consider them to be pests that need to be eliminated.

In Latin, this creature can be called “hairy worm” because the word Polychaete actually means “many hairs” and by the looks of the creatures there is no objection why the people who first discovered it settled on that name.

What actually is a bristle worm and how it affects my aquarium?

Currently there are almost 10.000 species of these worms, some of which live inside our aquariums. They have been classified by aquarists in 2 easy categories: the good worms and the bad worms.

What is interesting about these worms is that their size is hard to be determined. We can have a 8 cm bristle worm that can elongate up to 20 cm or even shrink down to 4 cm! This way they can fit in small holes and can easily move between aquarium decorations making them hard to spot.

Bristle worms find their way into our tanks when we introduce new natural decorations such as rocks and wood that have not been efficiently thermal treated (it is recommended that you boil every natural decoration that you want to introduce in your aquarium, this way you avoid a wider range of parasites, not only bristle worms).

Having one or two of those worms in the aquarium does not pose a problem, they will help by doing the clean-up job. But when their population exceeds more than 5 individuals you know there is something wrong and it needs to be fixed. Bristle worms multiply when they find a good food source, so if you have a lot of dead fish and wasted fish food on the bottom of the tank, then you must know that soon you will have a bristle worm tank instead of a fish tank.

Good or bad worms?

Like mentioned above, Bristle worms can settle in one of the two categories: good worms and bad worms. Most of the bristle worms that are found in salt water aquariums are good worms, they help clean up the tank and maintain a good water quality.

When it comes to bad worms, all aquarists fear the Fireworms. But not all Fireworms are bad, some of them are harmless just like the good ones, but there is one species in particular that catches our attention and that is the Breaded Fireworm (Hermodice carunculate). This one loves to chew on corals and it is a nightmare to have it inside the tank.

Fireworms tend to have more pronounced bristles with a reddish color at their base. Their body also tends to be more massive compared to other species of bristle worms.

Stings, doesn’t it?

The bristles, tiny hairy spikes, that these worms come equipped with are their defence mechanism against the outside world. The bristles are quite harmless, they don’t have any toxin or venom on them, the pain comes from the trauma of having dozens of them stuck in your finger.

Many fish tend to avoid them and some that are unlucky will have their scales torn apart by those tiny spikes. That’s why when cleaning up the aquarium or handling Bristle worms it is recommended that we wear protection gloves to avoid being stung.

If the inevitable happens, there are easy methods to get around the pain. Duct tape can be used to remove the spikes from the flesh and vinegar can be poured on the area to relive the pain. Why vinegar? Vinegar is an acidic substance that will counter the effect of the calcium (a base) that coats the bristles.

Getting rid of bristle worms

There are 2 ways to get rid of bristle worms. There is the natural way in which we add natural predators into the aquarium, such as: Pseudochromidae, Gomphosus varius, Cheilinus oxycephalus, Thalassoma lutescens, Stenopus hispidus or Stenorhynchus setrcornis. They will hunt and eat any bristle worm they can find.

The other way is by using bristle worm traps. These can be purchased from aquarium stores that sell them or they can be made using some basic materials from around the house. These traps are the same as kitchen bug traps, they let the worm get in and then it can’t get out.

A simple example of a homemade bristle worm trap consists of a taking a water bottle and cutting it 1/3 from the cap hole. After that the part with the cap hole is inserted upside down in the remaining section and it is glued using some non-toxic adhesive. The trap is then inserted into the aquarium and when a worm comes inside it, it cannot get out.

In conclusion

It is worth removing the worms from your aquarium? That depends on how you see the problem. If the bristle worm population is high it recommended to do some culling to reduce it. Some worms are beneficial as they clean the aquarium, eat dead fish and left over food and they maintain a good water quality.

Some people do not stand seeing strange alien like centipedes swarming inside their aquarium and they tend to be creeped by them. But in the end, it is up to de aquarist to decide whether to remove or to keep them. We do advice on keeping small worms as they have an important role in cleaning the water and maintaining a healthy aquarium ecosystem.

But to avoid them in the first place, every natural aquarium decoration needs to be cleaned and sterilized properly so they are not introduced in the aquarium and to feed the fish the right amount of food to avoid having left over food on the bottom of the tank.