Here we go everyone, this video is all about hitchhikers. . . mainly the top five that suck. Hitchhikers make their way into home aquariums by stowing away on pieces of live rock and coral. Some are relatively benign such as the occasional feather duster worm. There are even highly sought after hitchhikers such as commensal hermit crabs that live in some stony corals. This article however is not about those types of hitchhikers. In this article we will discuss my top five most problematic pests. Before addressing my top five, there are pests that are going to be noticeably absent, so let’s go ahead and give out some honorable mention awards. These pests can be annoying and prevalent but just didn’t quite make the cut for one reason or another.
First on the list of honorable mentions is Aiptasia. If you’ve never had them before,don’t worry, it’s just a matter of time. They are extremely prevalent in the hobby and are a huge nuisance mainly because they have great survival skills and they like to sting nearby corals. Aiptasia didn’t quite make the top 5 because they can be managed effectively by the introduction of certain fish such as copper band butterflies, peppermint shrimp, or Berghia nudibranchs. Their predators are so effective at eliminating Aiptasia the concern quickly turns to whether they might starve once the job is done. Also, while they pack a potent sting and can stress nearby corals, the damage they cause is relatively tame compared to the pests that actively feed on the corals in the aquarium. Similarly, Majano anemones don’t quite make the cut because it is possible to eliminate them entirely if caught early by manual removal. They do not have a particularly tight grip on their substrate and can be worked off the rocks and siphoned out. In tanks with medium sized populations, one can remove the rock work entirely and sit the rocks outside fora week or so to kill all the anemones. The last honorable mention award goes to bristle worms. They get a bad wrap most of which is pretty unfair. Bristle worms are a diverse group of invertebrates. Many are harmless and even make amazing detritivores that help the reef aquarium process uneaten food. It is for this reason that bristle worms are not in the top five. It is only a small minority that can cause trouble, and those can be found and removed, especially if we are talking about a large predator like a hobbit worm for example. If you do this hobby for long enough, it becomes routine to manage the low level pests that show up here and there. Over time, you learn new techniques to help mitigate the risk of hitchhikers, and sometimes a new product comes on the market that helps with a particular pest. All that is great! After a while though, something happens that I like to refer to as the Batman problem. Bear with me for a second. A long running theme in the Batman story line is the question whether Batman is actually good for Gotham City. On one hand,he cleans up the street by fighting crime, but that in turn creates a vacuum that draws in even more dangerous criminals. As time goes on, only the most violent and most deranged super criminals are left. That’s kind of what we do here. We eliminate the gangsters and petty criminals in our tanks and then comes the Joker, and now we have some serious problems the might take some extreme measures to handle. So after all that hype, let’s take a look at the top five!
Number five. . . Red Bugs. “Red Bugs” are small crustaceans that infest Acropora colonies. I liken them to fleas that irritate the coral and eventually causes polyps to stop extending fully. A greater concern is the potential for die-off which can lead to the loss of the whole colony. Acropora are a sensitive species and the colony can go down hill in a hurry. Red bug issues are difficult to diagnose because of their size. It is very difficult to see one of these specimens unless you know what to look for. They appear as small red dots on the skin of the Acropora colony. One trick to seeing them is to stare at a small portion of the Acropora and just pay attention to anything moving on the smooth surfaces. It gets easier to see them with some practice. Red bugs are resistant to
many of the commercially available coral dips on the market, which is odd because dips in general seem highly effective against most other crustaceans. Some hobbyists report having success using a dip in either Interceptor, a prescription pill for heart worm disease in cats and dogs or Bayer Advanced Insect Killer which you can find at a hardware store. This dip is great when you can remove the infected colony from the tank however in some cases the colony is too large to remove safely or has grown onto the rocks. In this case,you might consider using a product called levamisole, a commercial pig dewormer on the entire aquarium. Remember when we talked about drastic measures? This is a drastic measure. It is absolutely brutal on many of the tank’s inhabitants. It will kill all the beneficial inverts in the aquarium and it is going to stress out fish like you wouldn’t believe. It may be a good idea even to try and catch all the fish and inverts and relocating them to a quarantine system for a few days. Luckily, there is another method of dealing with red bugs in an established tank where the Acropora cannot be removed. Dragonface Pipe Fish are a close relative of sea horses and act as a natural predator of the crustaceans. They are surprisingly adept swimmers and constantly pick off microorganisms.
Ok, let’s move on to #4. . . Sticking with Acropora pests, we have Acropora eating flatworms. These guys can be tricky to see, so often it’s not possible to catch the problem early. One day, you might see these white speckles show up on Acropora and then you know you have an infestation. Those white speckles are the bite marks from where the flatworms were eating the coral, and there is a good likelihood that they are all over the coral. There is some good news and some bad news. The good news is, these flat worms can be removed by dipping. The flatworms let go of the host coral. In some particularly bad cases of flatworm infestation, what you thought was a brownish-tan colored Acropora was actually a white Acropora that was covered with hundreds of flatworms. Yeah. . . that was the good news. The bad news is, removing the adults probably won’t eliminate the infestation because they lay eggs and those eggs survive almost every dip. It may take weeks of diligent dipping to fully cure a colony. Let’s move on to #2.
Zoanthids on one hand are one of the easiest corals to keep in the reef keeping hobby. On the other hand, they are also one of the most susceptible to awide range of pests. One such pest is the Zoanthid Eating Nudibranch. This variety of Nudibranch was particularly well disguised because as they eat the Zoanthids, they take on the color and fluorescence of the polyps. After a while, they look just like another head in the colony. Here is one that’s been isolated. These nudibranchs can be removed by dipping in commercially available dips but like the Acropora eating flat worms, their eggs survive and can be very difficult to remove. The eggs form a spiral pattern and have a thick gel coat making them difficult to remove with metal scrapers and brushes. What seems to work better is a dry paper towel. The paper towel dries out the gel coat and are coarse enough to pull them off the polyp. Despite the effectiveness of dipping to kill the adults and physical removal of the eggs,an infestation of Zoanthid Eating Nudibranchs is still difficult to manage because unlike many pests that only stick to the coral, these pests are perfectly comfortably roaming the tank looking for new colonies to eat. Even if the hobbyist was diligent and purified every single zoanthid colony, it is likely these sea slugs are still hiding somewhere in the rock work and can reemerge later.
Ok Number Two. If the nudibranchs weren’t bad enough there is a second pest that plague Zoanthids and is the stuff of nightmares. There is a variety of sea spider gobbles up Zoanthid colonies. If you are familiar with the Alien movie franchise, these sea spiders are the face hugger aliens of the reef aquarium hobby. They latch on to the Zoanthids at the mouth of the polyp and lay eggs inside the polyp. Later as the spiderlings hatch the polyp disintegrates in to a grey mess. I’ve isolated one that I found a long time ago. They are super creepy and can cause widespread damage so if you see your zoanthids staying closed for extended periods of time and turn to mush, take a close look for these guys. These sea spiders can be physically removed with tweezers and dental tools. Commercially available pest control dips are also effective at killing them if given enough time in the bath. The eggs however are completely unaffected by either method of removal because they reside deep within the tissue of the polyp. It takes several rounds of removal to get rid of a spider infestation and can be a frustrating process especially because during this whole time the Zoanthid collection looks like it is dissolving before your very eyes.
It’s time for number one. It’s the Montipora Eating Nudibranch and the bane of my existence. They are one of the most difficult pests to manage and are frequently imported on wild colonies. They are so bad in fact that I now consider discarding a coral infested with them rather than trying to eradicate the nudibranchs. The Montipora Eating Nudibranch is white in color and tiny compared to the Zoanthid-eating variety. They can be difficult to spot at first because they tend to start working on the bottom of the colony. Removal of this variety of nudibranch is more challenging than any other I have had the displeasure of dealing with. First off, they are resistant to dipping. The adults do succumb in time to an aggressive dose but can shrug off most regular concentrations of coral dip. The eggs are difficult to remove and require scraping of the coral’s skeleton to dislodge. Even with careful extraction of the eggs, they are small enough that many go undetected only to hatch later. This past year, we attempted sequential dips to where we dipped certain corals over 50times. In the end, the nudis seemed to disappear but then once summer came along they reappeared suddenly. Given their persistence and considerable damage they are capable of, the Montipora Eating Nudibranch is a top tier pest in the hobby today.
Hitchhiker pests unfortunately are a reality in the reef keeping hobby. As a conscientious hobbyist, one can never ever assume that a coral or rock is clean because it comes from a seemingly good system. Developing a systematic approach to new coral introduction is worth its weight in gold if it successfully prevents just one outbreak. Some combination of preventative dips and quarantine will help immensely as will purchasing from aquacultures sources as those corals are more likely to have undergone dipping themselves. Ok, that in a nutshell is my top five list of horrible pests. Let me know if you agree or disagree and list your worst in the comments below.