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Montipora-Eating Nudibranchs and Treatment

reefdup Identification, Montipora-Eating Nudibranchs May 29, 2021May 29, 2021Coral, Montipora, Montipora-Eating Nudibranchs, Nudibranch, Phestilla, subodiosus 0 Comment

Montipora-Eating Nudibranch on Digitata Coral

Growing…growing…gone. Unfortunately, this is an all-too-common story in the reefkeeping hobby due to a pest aptly named for its favorite meal, the Montipora-Eating Nudibranch (Phestilla subodiosus). Although treatment of Montipora-Eating Nudibranchs is historically challenging, this article covers several available options.

Montipora-Eating Nudibranchs (M.E.N. – just kidding, I won’t use that acronym) are from the phylum Mollusc, class Gastropod, sub-class Opisthobranchia, order Nudibranchia. From there, they are of the suborder Aeolidina, superfamily Fionoidea, family Trinchesiidae, genus Phestilla, species subodiosus. Identification down to the species level was only accomplished as recently as 2021, although the hobby has been actively fighting them since at least the early 2000’s (Wang, et al., 2020).

How to Identify:

These nudibranchs are white in color and range in size from 1-3mm in length. The body is covered in cerata, which may store the nematocysts (stinging cells) of the coral to help protect them from predators. Shown in the picture is a single Montipora-Eating Nudibranch (circled in red) at the edge of a Montipora digitata coral.

Montipora-Eating Nudibranch on Montipora Coral

The key to detection is to understand the life cycle of these nudibranchs. If there is only one nudibranch, it is capable of reproducing asexually. The adults lay tiny clusters of 3-20 eggs (Borneman, 2007) in crevices along the base of the coral (see image). As the eggs hatch, the juveniles immediately join the adults in eating the coral in a distinct jagged line along the base and edges. Reportedly, these nudibranchs can survive extended periods with no food source.

Modeling the Lifecycle of Montipora-Eating Nudibranchs

Back in grad school, I modeled the lifecycle of these nudibranchs and how various treatments worked on them. Unfortunately, the results were never promising once the nudibranchs established themselves in a mature tank. (Note: Sadly, I built this model with an educational license, and my files are “legacy file types” for the software. I have been unable to regain access to my work for either historical purposes or additional research.)

Montipora-Eating Nudibranch Treatment Options:

Treatment for the Montipora-Eating Nudibranchs comes in the forms of prevention, natural predators, chemical destruction, and manual removal.

Treatment Method 1: Prevention of Montipora-Eating Nudibranchs:

Prevention lies in purchasing from a reputable dealer or hobbyist first and foremost. Chances are, if the person has had them before, that person will have them again. Next, the responsibility falls to the new owner of the coral in proper quarantine procedures (at least two months is recommended). Examination with a magnifying glass is recommended to help identify and remove eggs. However, the nudibranchs might have laid eggs in a hidden crevice. Since the eggs are laid at the base of the coral or on dead coral skeleton, some hobbyists chose to remove the coral from the base rock. Both remaining coral on the rock and base rock then dies. This is to help ensure that the eggs are not transferred.

Treatment Method 2: Controls for Montipora-Eating Nudibranchs

Some hobbyists have found certain natural predators will help control the nudibranchs. Unfortunately there are no known complete eradication measures available naturally. The wrasses generally known to eat most invertebrates will most likely also feed on the nudibranchs. It is important to keep in mind that as far as natural predators go, what works for one hobbyist may not work for another hobbyist, especially with wild creatures.

Treatment Method 3: Coral Dips for Montipora Eating Nudibranchs

The last method of eradication is by chemical means. Coral dips often help stun the pests so they can be blown off gently with a pipette or powerhead. These adult Montipora-Eating Nudibranchs (as pictured) were in a dip much longer than the coral colony could survive. Unfortunately, that is typically the case; however, there are a few less lethal options.

Montipora-Eating Nudibranch Treatment: Iodine

Many hobbyists have found that an hour-long dip in iodine will kill most adult nudibranchs. However, this may cause undue stress to the host coral, especially if flow, pH, and temperature are not ideal in the dip.

Montipora-Eating Nudibranch Treatment: Levamisole

Levamisole (a pig dewormer available at farm supply stores), has been used in a similar manner to the iodine dip, but with a higher fatality rate to the host coral. Levamisole paralyzes the nudibranchs so they can be removed more easily from the coral.

Montipora-Eating Nudibranch Treatment: Potassium Permanganate

Another chemical method is potassium permanganate. The dip (50mg/l for 30-90 minutes – Borneman, 2007) has been shown to effectively destroy both the adults and the egg masses with moderate impact to the coral. After eradication on the corals, the main tank should be kept free of Montipora for approximately two months.

Like all chemicals, caution should be exercised when handling potassium permanganate. Using an MSDS (Material Safety Data Sheet) to learn about the hazards of use and what protective gear is highly recommended. An MSDS for potassium permanganate suggests the use of eye protection, gloves, and respiratory protection as potassium permanganate can cause serious burns to the skin, nose, and throat.

Montipora-Eating Nudibranch Treatment: Series of Dips + Manual Removal

Rather than trying to kill both adult nudibranchs and eggs, I attempt to just break the lifecycle by removing the adults so that they cannot reproduce. When I get any frags of Montipora, I perform my usual coral intake process. I perform an inspection, remove the plug/base/dead skeleton, perform dips with manual pest removal, and attach a new base. Then I place the coral into my quarantine tank, but it stays for an extended period (60 days rather than the typical 30 days).

Since a succession of coral dips work for AEFW and red bugs, I also dip all Montiporas daily the first week to aid in manual removal. After that, I dip every other day the second week, every third day the third week, and then once a week for weeks four through six. I have not lost a single coral with this method, and it saves me the hassle of treating with different medications for different parasites at different times.

Various dips may work to stun the nudibranchs, and examples include CoralRx, Revive, and Tropic Marin Pro Coral Cure. Again, here the goal is to simply aid manual removal by stunning the adults. If the adults are removed, the eggs will continue to hatch in the presence of food. Adults are then easily removed before they can reach maturation. In the lifecycle model mentioned above, this was the most successful approach when implemented correctly.

Montipora-Eating Nudibranch Treatment: Display Tank + Dips

The worst challenge is a display tank with mature colonies infested with nudibranchs. My best advice is to consider the coral dip series described above (although large colonies may require buckets for treatments). Additionally, the hobbyist would have to kill any bases left attached to the rock along with unremovable encrusted Montipora colonies. Another option, if the colonies are smaller, may be for the hobbyist to remove all Montipora from the display tank. The hobbyist would then place all removed Montipora into a quarantine tank for treatment, minus a sacrificial frag that stays in the display. The hobbyist must then frequently replace that sacrificial frag so as to draw out the nudibranchs from the rockwork.

Montipora-Eating Nudibranch Treatment: Other Dip Options

Hobbyists have used garlic and freshwater dips with nudibranch mortality but they also often report high coral mortality.

Conclusion:

Although there are still no full-tank chemical treatments, eradicating Montipora Eating Nudibranch is possible with patience and proper husbandry. Using a combination of dips and manual removal seems to be the most effective option available at this time.

Red Bug Parasites (Tegastes acroporanus)

reefdup Identification, Red Bugs May 29, 2021October 16, 2022acropora, AEFW, Bayer, Coral, Interceptor, Milbemax, red bugs, small polyp stony, SPS, Tegastes acroporanus 4 Comments

Somehow back in the day, after over five years of having SPS-dominant aquariums, I got my first case of red bug parasites. A local aquarist was tearing down his system and gave me a few corals that weren’t doing well. Turns out, red bugs AND Acropora-eating flatworms (AEFW) infested the corals. Fortunately, I caught the red bugs while the Acropora was still in my quarantine tank.

Red bug parasites (Tegastes acroporanus) are extremely tiny copepods (as seen in the red circle in the photo) that solely infest Acropora corals (not Montipora, Pocillopora, etc.) They come into the hobby on wild or maricultured colonies (corals purposefully grown and harvested in controlled ocean environments), and hobbyist selling/trading of aquacultured corals further spreads them.

A good indicator of a red bug infection is a loss of Acropora tip coloration and browning that cannot be attributed to other factors. Red bugs caused the coral shown to lose nearly all coloration, while AEFW caused the white patches.

In the early 2000’s (now I’m dating myself), there was a general consensus in the reefkeeping hobby that red bugs only affected smooth-skinned Acroporas. Hobbyists assumed they did not bother corals like Milleporas or “the green slimer” due to the extra mucus they produce. Although red bugs do tend to prefer certain Acropora (especially Acropora valida, the “tricolor”), most every Acropora species is susceptible. Hobbyists also commonly believed that red bugs laid eggs and had a larval stage. This led to a consensus that three treatments were needed in order to eliminate the red bugs entirely. Although research eventually determined that red bugs are live bearers, I still recommend three treatments just as a safety precaution.

How to Identify:

On Acropora corals that have “browned out” due to red bug presence, the red bugs are rather distinguishable. They are mostly yellow (almost a gold color) with a bright red dot. They are also extremely tiny at around 0.5mm (think a little bigger than the size of the period at the end of this sentence). Unfortunately, they are not easy to see on healthy corals, and they have an ability to hide within the coral polyp itself without being consumed. In order to determine the presence of red bugs, I use a magnifying glass to look for them before placement into my quarantine system. After that, I observe the coral daily for a week. I also take a photo of each coral and zoom in to look for anything I’ve missed.

How to Treat Red Bug Parasites:

Unlike other serious pests (e.g., Montipora-eating Nudibranchs), there is a suitable in-tank treatment for red bug parasites.

Method 1: Control

Some hobbyists believe that blowing the corals off with a powerhead a few times for a couple weeks will rid the Acropora of red bugs since they may starve before finding their way back to the coral. Other hobbyists rely on natural predation (e.g., pipe fish, file fish, gobies, wrasses), but to my knowledge, no predators have a 100% success rate. I advise against natural control methods for aquarists who plan to sell/trade their corals.

Method 2: Coral Dips

Coral dips often help stun the pests so they can be blown off gently with a pipette or powerhead. Since red bug parasites are live bearers, this method can work as long as all the red bugs are removed. Since a succession of coral dips work for AEFW and red bugs, I dip all Acroporas daily the first week. After that, I dip every other day the second week, every third day the third week, and then once a week for weeks four through six. I have not lost a single coral with this method, and it saves me the hassle of treating with different medications for different parasites at different times.

I should note that I’ve never found a pest after week two, but I still go the full six weeks since the lifecycle of AEFW is quite long (and I always treat for both AEFW and redbugs). Also, some dips can be extremely damaging to smooth-skinned corals, so please use caution if you plan to treat one of these.

Coral Dip Treatment Protocol for Red Bug Parasites:

Follow dip manufacturer instructions.

Method 3: Prescription Flea Medications

Before the manufacturer discontinued it, hobbyists considered Interceptor (milbemycin oxime), a prescription canine flea medication, as the golden standard for red bug parasite treatment. However, as it killed all shrimp, crabs, and other crustaceans, aquarists had to remove them before dosing (the pod population recovered with time). This die-off would also spike ammonia levels, so reefkeepers had to be prepared for a water change and to run carbon. Many people had difficulty obtaining Interceptor from their veterinarians since treating for red bugs is an off-label use. However, the Veterinary Information Network (VIN) published information on red bug parasites for reference.

Once Interceptor was no longer available, reefkeepers began searching for a replacement. Currently, Milbemax is the most often recommended replacement. It is a prescription combination of milbemycin and praziquantel. (The latter medication is commonly used for fluke treatment in reef tanks (e.g., PraziPro); however, it is a much lower dose than would be effective for common marine flukes).

Providing proof of infection to a veterinarian and asking him/her to look up red bugs on the VIN should be enough to receive the medication (or at least it was for us.) Some veterinarians have recommended different medications with different treatment protocol (e.g., MilbeMite Otic), so those individual cases are not discussed here. Unfortunately, many aquarists are finding some red bugs have a resistance to milbemycin. If you try it with no success, work with your veterinarian to find an alternate medication or try one of the other methods listed here.

Interceptor Treatment General Protocol for Red Bug Parasites:

(This is provided for historical purposes only since Interceptor is no longer available, as it may be relevant to other treatments.) Dustin Dorton of ORA determined 0.025 grams of Interceptor are needed per 10 gallons of water. After that, the protocol is the same as Milbemax, described below.

Milbemax Treatment General Protocol for Red Bug Parasites:

(Obtain actual procedures from a veterinarian, as this is for general reference only.) The recommended dosage is 23mg per 400g tank water, which works out to 0.0575mg per gallon tank water (or 5.75mg per 100 gallons if that is an easier reference point). Similar to Interceptor medication, pulverize and weigh the medication out as accurately as possible. Estimate the true volume of water as close as possible (subtracting live rock, sand, etc.)

Remove all crabs, shrimp, and other crustaceans from the aquarium before dosing. Turn down the skimmer so that water runs through it, but the skimmer doesn’t actually skim. Remove GFO and activated carbon. Add an airstone (or multiple, depending on the size of the tank) bubbling gently to help maintain the pH. Otherwise, allow everything else to run so that the chemical can spread throughout the aquarium. Dose the correct amount and let the system run for six hours.

After six hours, the red bugs should be gone, but if they are not, slightly adjust the dosage and try again in a few days. Perform a water change (~15-25%), turn the skimmer back up, and bring the GFO and carbon back online. As mentioned above, although red bugs are live bearers, three treatments a few days apart is still ideal. Once the red bugs are completely eradicated and the medication is removed, reintroduce the crabs, shrimp, and other crustaceans to the aquarium.

Method 4: Bayer Advanced Insecticide

WARNING: Per Bayer Advanced Insecticide’s labeling, “It is a violation of Federal law to use this product in a manner inconsistent with its labeling.”

Yes, this is the stuff you may have in your garage or at your local hardware store. Some aquarists use it as a dip only, not as an in-tank treatment. This website does not cover Bayer use as a coral dip, due to the warning above.

Method 5: Temperature Adjustment

With crazy heat in the summers, lowering the tank temperature may not be feasible. But for tanks located in basements during the winter, this may be the least expensive option. In fact, this method worked for me…accidentally! Right after I received the infested Acropora mentioned above, we lost power for about six hours. My quarantine tank got down to about 65 degrees (thanks to being in Utah in the middle of winter). After the power came back on, there were no signs of red bugs. I’m not the first to document this. I still continued treating for them just in case, but I never saw another one. This seems to work, but we still need scientific studies to back it up.

Experimental Temperature Treatment Protocol for Red Bug Parasites:

Slowly lower temperature to 65-66 degrees. If tank inhabitants start to show signs of stress, start bringing the temperature back up. Leave the temperature at 65-66 degrees for 4-6 hours. Note: this is experimental, and there is not enough data to determine if this treatment works 100% or is safe. Use with caution!

Conclusion:

Acropora Rehabilitation Before and After

Thanks to all the courageous mad scientist reefkeepers out there, there are several proven treatments for red bugs, including an in-tank treatment. The Acropora shown was saved from both red bugs and AEFW! Hopefully, with the increasing ease of treatment protocols, red bugs will be a thing of the past. Best of luck in your treatment!

Dying Lithophyllon Coral Rehabilitation

reefdup Lithophyllon, Rehabilitation February 8, 2021February 8, 2021carbon, chalice coral, Coral, Dying Coral, flatworm, Lithophyllon, poison, quarantine, Rehabilitation, Rescue Coral 0 Comment

A local fish store (LFS) called me to ask if I wanted to try to save some of their corals. An employee had overdosed their reef tanks with a chemical used to treat flatworms (I was not told what chemical it was). When I arrived, honestly, I was shocked at how bad many of the corals were. I don’t know if these corals were dying from an overdose of some unknown chemical or if the flatworm toxins were killing them. Either way, something was poisoning these corals to death. I picked up two “chalice” corals, amongst others. These dying Lithophyllon coral mouths were gaping open, the tissue was falling off, and what tissue did remain was barely hanging on. Rehabilitation was going to be dicey. (Photo of Litho#1 taken 11 May 2013)

Dying Lithophyllon Coral Inspection and Dipping:

When I brought them home, I temperature acclimated them to my quarantine tank and prepared the dips. Like most of my rescues, I dipped the corals for pests. (Photo of Litho#2 taken 11 May 2013)

*NOTE: This post tracks the corals as “Litho#1” and “Litho#2” to show individual progress.

Coral Quarantine:

After the dips, I placed the two dying Lithophyllon corals into my quarantine tank in a low light, low flow area. I made sure that no crabs would bother the coral, especially with all the decaying tissue. Since the corals were poisoned, I made sure the quarantine tank had new carbon to help absorb anything that the corals might leach. Both corals did start to quickly recede, so I tried to stop it by smearing a bead of superglue gel along the receding edge (white lumpy band in the photos below). Rehabilitation was definitely already proving rough. (Photo of Litho#1 taken 11 May 2013)

Receding Lithophyllon Coral (Photo of Litho#1 taken 9 June 2013)

The corals also refused to eat until about a month after I received them. I started them on fish food pellets (shown here and above) since they are quite processed. In my experience, sick corals seem to digest fish pellets better than whole foods (like mysis, etc.) This helps them recover faster. (Photo of Litho#2 taken 9 June 2013)

Coral Grow-Out:

After stopping the recession with superglue and maintaining regular feedings, the corals started to heal quickly. And how great they started looking! After 30 days in quarantine, I inspected, re-dipped, and placed them into the grow-out tank. (Photo of Litho#2 taken 4 August 2013).

Regular feedings likely helped the coral recover. (Photo of Litho#1 taken 12 October 2013)

Here is Litho#2 on 3 November 2013.

A month later (8 December 2013), Litho#2 was growing down its skeleton.

Fully Rehabilitated Lithophyllon Coral:

Nearly a year later, both previously dying Lithophyllon corals were growing rapidly. This Litho#2 is shown on 1 May 2014, when it was fully rehabilitated. Below is a close-up shot showing the corals’ beautiful patterns.

Conclusion:

I had very little hope for these dying Lithophyllon corals due to their poisoned state. However, the fast reaction of the LFS along with continued care over a year fully rehabilitated these two corals. Shown below are the before/after photos of the dying Lithophyllon coral rehabilitation. One coral was nearly immediately rehomed, and the other coral was rehomed a couple years later.

Dying Cyphastrea Coral Rehabilitation

reefdup Cyphastrea, Rehabilitation February 2, 2021October 16, 2022Coral, Cyphastrea 0 Comment

Cyphastrea coral are usually very hardy and prefer low light (and sometimes do best partially shaded) but can be acclimated to higher-light areas. They also adapt well to a variety of flow conditions. I received this dying Cyphastrea coral from a reefkeeper who was getting out of the hobby. Good husband would likely be key to this coral’s rehabilitation. (Photo taken 22 May 2012)

Unfortunately, most corals in the tank were suffering from poor water quality, and this Cyphastrea was no exception. The reefkeeper did the responsible thing by recognizing that the corals needed proper care and attention.

Note how some of the polyps still have tissue while there is no tissue between the polyps. This is a good indication of poor water quality (in addition to actually speaking with the previous owner). Regardless of the damage root cause, I still dipped and checked it for pests.

Coral Quarantine:

As mentioned, the coral was declining due to poor water quality. After the initial dipping process, I placed the coral into my quarantine tank for observation and acclimation. Here, the coral was fairly low in the tank to allow it to adjust to the lighting. Notice that by less than a month later (15 June 2012), the coral was already regrowing!

Just another 15 days later (30 June 2012) and slightly over a month total time with me, and the coral was gaining coloration and growing rapidly! Given the proper light and water conditions, this coral grows extremely
fast.

Fully Rehabilitated Coral:

This previously dying Cyphastrea coral was completely rehabilitated in less than three months (pictured at 14 August 2012). The coral had completely covered the old skeleton and had encrusted onto the base. In fact, it started to grow so quickly, that I had to frag it several times. Coral reproduction via fragmentation reduces hobbyist impact on the oceans.

Troubleshooting Dying Cyphastrea Corals

As mentioned above, if the Cyphastrea coral has started to lose tissue between the polyps, then there is probably a water quality issue. If the coral is bleaching, then it’s likely in too high of light (or might’ve been in absolutely no light.) If the coloration isn’t great (too brown), then it may need more light or less nutrients. Or, if there’s recession from one side to another, then it may be a pest, bacterial/fungal infection, or a sudden water quality problem.

Plerogyra Rehabilitation

reefdup Plerogyra, Rehabilitation May 30, 2020January 17, 2021Bubble Coral, Coral, Dying Coral, Plerogyra, Rehabilitation 0 Comment

This Plerogyra (“bubble coral”) was significantly damaged on 14 July 2012. The damage was so new that the tissue was still attached.

Although the coral looks worse here (15 August 2012), the damage was stopped.

By 7 October 2012, the coral was mostly recovered and growing again.

Here, the coral is completely recovered and beautiful! (21 October 2012)

Only three months went by between when this Plerogyra (“bubble coral”) was damaged and fully recovered.

Lobophyllia Rehabilitation

reefdup Lobophyllia, Rehabilitation May 30, 2020January 17, 2021Coral, Lobophyllia, Rehabilitation 0 Comment

This Lobophyllia coral was badly receded, as shown by the remaining pink skeleton. 14 July 2012

By only a month later, on 14 August 2012, the coral was mostly healed and regrowing.

About six months later, 6 January 2013, the coral was fully healed and growing well.

Although the coral’s growth rate was not ideal, by 11 August 2014, it had formed a second polyp. Coloration was also phenomenal.

In 2.5 years, this Lobophyllia coral went from nearly dead to thriving with a new polyp.

Trachyphyllia Rehabilitation

reefdup Rehabilitation, Trachyphyllia May 25, 2020June 27, 2020Coral, Rehabilitation, Rescue, Trachyphyllia 1 Comment

This Trachyphyllia (?) came in on 2 June 2012.

By 14 August 2012, the coral’s center recovered.

By 6 January 2013, the coral was nearly healed, with a circular shape.

After roughly a year and a half, on 8 December 2013, the coral was back to its full glory.

Dying Homophyllia Bowerbanki Coral

reefdup Homophyllia, Rehabilitation May 24, 2020February 25, 2022Acan, Bowerbanki, Coral, Homophyllia, LPS, Rehabilitation, Rescue 4 Comments

This dying coral (Homophyllia bowerbanki) was found injured at a local fish store on 10 February 2013. A fish had been nipping at it, which made diagnosis easy. This was a low risk rescue for me, and Homophyllia bowerbanki is my favorite species of coral – a win!