The Nudibranch’s actual length is about 1 ½ inches. It blends in nicely with the color of the coral. Beware there are other Nudibranchs that blend in on other corals and eat them also. Shown right is a photo of its eggs. Thanks Richard F. for the photos and the discovery.

There are hundreds of Nudibranchs each having a specific diet that can attack specific corals. Montiporas and Acroporas especially.

Things you can do to remove a nudibranch.

If you can lift the coral out of the tank. The coral can be out of water as long as needed so don’t worry. Have ready a clear glass baking dish if possible. Also a flashlight, tweezers, an empty syringe, a cup of freshwater, and possibly a magnifying glass. When the leather comes out the water he’s going to shrink slowly – that’s OK. Hold the leather over the baking dish and flush his hole at least 3x with room temperature TDS=0 freshwater [3 x 10cc or equivalent]. That should do it. You have the tools to possibly look inside. Check the dish for the nudi’s body. Inspect for eggs on the outside of the leather and wash off with freshwater. The leather coral will start regrowing filling the hole quickly if the nudibranch is gone.

If you can’t lift the leather out of the tank. Rig airline tubing to any size syringe [5cc or larger]. The procedure is essentially the same. Having two people helps on when one person squirts and the other aims


There is a white flatworm that is harmless – it’s the brown ones that are bad news.

Brown Acoel flatworms

Acoel flatworms are harmless but can quickly multiply into plague numbers and can completely cover a coral – starving it of light. They can be siphoned off with relative ease when in large numbers. If they do cover a coral you can give the coral a 25 to 30 second BETADINE dip. Detritus and other nutrients are flatworms main food source. Don’t over feed and use Liquid Gravel Vac by Tropical Science to eliminate sediment buildup. Dip preparation:  Using a white bucket with enough tank water to cover the coral, add about 15 drops of Betadine [sold under many names].  Swirl the water.  Your goal is a very light tint of color.  Add more if needed.  As long as the water is colored it disinfects.  More Betadine can be added for more dips.  Discard when finished.


There are 3 flatworm treatments available.  Flatworm Exit by Sailfert, Flatworm Rx by Blue Life, and Flatworm Stop by Korallen-Zucht.  All 3 work differently.  Be prepared to change water, run carbon, and empty your skimmer.

Flatworm Exit – we often 2x or 3x the dosage and run the Exit several hours to overnight. . Do not under treat or shorten the treatment time because if some survive they will have built up a tolerance and subsequent treatments will not work. Copepods and inverts like brittle and serpent stars, and acropora crabs and are known to react negatively to Exit but most survive.

Flatworm Rx – similar treatment as Exit using a different medication and more invert friendly.  Rx works well on flatworms with a tolerance for Exit.

Flatworm Stop – exceptionally good for Acropora and Montipora flatworms.  Be aware flatworm eggs are not killed so future treatment is necessary.  It does help very well with coral recovery and growth.  Fish will eat these flatworms if you first blow them off with water.

Use Exit or Rx as a dip when you bring in new corals. Excellent results have been reported using diluted ant killer as a dip. Use with extreme caution. This treatment will kill everything except sps corals. LPS and soft corals haven’t been checked yet. Rinse coral in clean saltwater after dipping.


These fish are known to eat flatworms but don’t expect fish to eradicate them.  Flatworms reproduce faster then they can be eaten.

Melanarus Wrasse

Springers Damsel

Six Line Wrasse


Your choices in flatworm medications are above.  Notice their shape is more rounded than the brown acoel flatworms above.



Aiptasia- A Brief View

Aiptasia are shown here. They are light brown, very thin tentacled anemones.

You can have as many Peppermint Shrimp in a tank as you’d like. They will spawn quite easily, but the young are usually eaten.

Aiptasia sp. anemones, also referred to as rock or glass anemones can be a real scourge on any marine tank. They multiply like rabbits, damage or kill other marine inhabitants, and are difficult to get rid of. Intense lighting is one reason these hardy pests to do so well in a captive environment. They also multiply significantly in aquariums with poor water quality and tanks that are over fed. If these anemones are not removed or destroyed, they will overrun an aquarium in a very short period of time. You cannot just pull or scrape them off because any little piece that is left behind will just re-grow. So what do you do?  All your choices are on Aiptasia- A Comprehensive View 

Shrimps – There is a lot of debate about using peppermint shrimp. It looks like these little shrimp will do the job, but the concern is they are not reef safe. Be sure you get the correct type of shrimp. The Camelback (Rhynchocienetes uritai) and the Peppermint (Lysmata wurdemanni) are very similar in appearance, but they are NOT the same. It is important the you learn how to properly identify these two species! The Camelback is often misidentified or misrepresented and sold as a Peppermint shrimp, but the TRUE Peppermint shrimp is the L. Wurdemanni. It is the real aiptasia eater and is considered to be reef safe, where the R. uritai is less likely to eat aiptasia and is NOT reef safe. I’m told to be aware of captive raised Peppermint shrimp eating SPS corals.

Notice the hump on the Camelback’s back and the brighter color.

Peppermint have different front pinchers to.

Mantis Shrimp

They fit into the Crustacea phylum in the class Malacostraca, subclass Hoplocarida (which means “Armed Shrimp”), and order Stomatopoda. They are most often referred to as Stomatopods. They come in what seems like and endless variety of species. They are found in tropical waters worldwide.  They are carnivorous and will eat just about anything and everything. They are experts at catching and killing prey, being very clever, stealthy hunters. They are masters at hiding. They are not related to shrimp, but are referred to as shrimp because of their front appendages and how they use them to capture food. They are called a “Mantis” Shrimp due to the fact they resemble the appearance and have the same hunting characteristics of a praying mantis insect. There are two hunting categories, the “spearers”  and the “smashers”. The “spearers” use their spear-like claw to silently stab soft tissue prey. The “smashers” use their forceful, club-like claw to hit, crack open or pulverize harder bodied prey. It is interesting that the power of the “smashers” appendage can produce a blow close to the power of a .22 caliber bullet and are notoriously known as “thumb splitters”. These animals are burrowers, and can create tubes or cavities in sand, rubble or mud. They will adapt to living in holes, cracks or crevices in rocks, and may take up residence in snail or hermit crab shells as well. They are solitary animals, and unless you have a VERY large tank, they should be kept alone. 

Bristle Worms

Contrary to public opinion, Bristle Worms (Polychaeta = Many Bristles) are not bad for your tank, unless they get very large or are found in massive numbers. This happens when you over feed the tank because they will mutiply to meet the available food source. Cut back on feeding and they will slowly die off and eat their dead. They serve a useful function by keeping your tank clean and your sand or gravel “moving”. Should Bristle worms get 5 to 6 inches, pull them if possible using tweezers or needle nose pliers, NOT your fingers unless you’re wearing gloves. Should you get stuck with bristles, use duct tape to gently lay it over the bristles and then pull off. Hot running water helps with the sting.

Arrow Crabs

Arrow crabs are great Bristle worm eaters but they also love to eat snails, hermits, shrimp, and small fish.


A Polyp Eating Snail

Look closely and you may find these on your Zooanthind polyps munching away. The lines in the photo are from a yellow legal pad for size comparison.

Peacock Mantis Shrimp

This Peacock Mantis Shrimp is about 4 to 5 inches long. This is a really cool creature but they must be kept in a tank by themselves. They reach 12 inches in length.

Harlequin Shrimp

Harlequin Shrimps main food source are starfish. You can have them in reef tanks but you will have to buy chocolate chip starfish as food. They will eat all types of starfish so beware.   Brittle and serpent stars usually get away.  You can keep them in a reef tank if you buy feeder starfish.

Unwanted Starfish    Asterina wega

Asterina wega                    

Here is a real nuisance of a starfish. If you see any in your tank, pull them out because they reproduce very quickly. They can be controlled by Harlequin shrimp but the shrimp will also eat other starfish. The little photo is about true size – about 1/2″ across. The photo on the left was taken on a legal pad so you also have another frame of reference. Note their irregular shape.


The Sea Apple is a beautiful somewhat anemone-shaped cucumber, and has rows of tube feet along the vertical length of the body. Its head area has a ring of feathery tentacles, which it uses for collecting phytoplankton.  They range in size up to about 6 inches (15 cm), and when they find a spot to their liking, may remain there for years.






There are also worm-like cucumbers called Medusa worms. These legless sea cucumbers are members of the family Synaptidae (Order: Apodida). They all look quite similar with soft and flaccid bodies with rounded knobs. They project their tentacles directly into the substrate to collect organic coated particles. They are relatively nontoxic when compared to  the Sea Apple BUT THEY SHOULDN’T BE CONSIDERED SAFE. The most common genera are Euapta, Synapta and Synaptula from the Indo Pacific. Those from the Caribbean are usually Euapta lappa or Synaptula hydriformis.



The Dreaded Majano Anemones

This is one to watch out for.  They are extremely hard to kill.   AIPTASIA CONTROL by Blue Life works great. Just follow directions but do not kill Majanos in large numbers.  Their remains can foul your water.  Use carbon and skimming to clean your water.  One customer has reported that Heniochus (bannerfish) will eat these pests – but be aware they are not safe for other corals.  Aiptasia eating filefish (leather jacket) will also eat them and sometimes zooanthids.

Hair Algae

The greatest cause is not changing filters 2 to 3 times per week, feeding more than once a day, feeding flake food, dry food, “gumbo” foods. Also not doing 1 time per month very large water changes.  You will find other reasons in my website.  SEA HARES are great for eating hair algae, we often have them in the shop.

See Problem Solver and Caulerpa & Seaweed for ideas to fight Hair Algae.

Polychaete Worm

Specifically a Spaghetti worm

Spaghetti Worm

The tentacles are used for feeding… It’s a surface feeder and can  live in tubes or under rocks. It’s entirely reef safe, and it might even be considered beneficial. Spaghetti are related to bristles. Their tubes are made of mud and mucous.




Dragon Face Pipefish are red bug eaters


See our coral dips at top of this page


This guy was pulled from an Acro Colony after 3 adjacent colonies (different species) had shown white patches and white tips.

Photos from Dominic



Unknown Species of Flukes

An unknown species of flukes appeared in day.  A large dose of Marine Max knocked them out very quickly.


Below are examples of Ick when it’s too late to treat the fish and save them. Marine Max and copper both work in the early stages – see our Disease Chart for more information.

When fish have this many parasites attached there is 0% chance of saving them. You MUST start treatment at the first sign of infestation.


I call them that because they pull their claws in tight and are shaped like a box   They’ll flip large corals and rocks looking for copepods and worms. Remove them if you find one.

Linkia starfish with a bacterial infection

Any species of  starfish cannot recover once infected. It is contaigous to other starfish.

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