Parasites are a common occurrence in any hobby and we as pet owners deal with them on a regular basis. Parasites are nasty opportunistic organisms that latch onto animals (in our case, fish) and feed on their blood, tissue, fluids and a variety of other things. It is a one way relationship that benefits the parasite but not the host. Together with bacterial, fungal and viral, it is one of four major cause for undue stress and death in infected livestock.
The most common parasites we deal with and have the most experience with are the ubiquitous Cryptocaryon, Amyloodinium, and various other common diseases which are caused by tiny, single celled ciliated protozoa. Macro parasites such as parasitic isopods, and in this case leeches, are more uncommon, especially the latter.
Leeches are rare, and are a very poorly studied group of parasites. We consulted with Tetsuo Otake, an expert in marine fish diseases amongst other things, and he thinks they could be from the family Piscicolidae. The genus and species however, are not known as leeches are not well documented. As mentioned, these are rare and not your average parasite that you encounter daily.
The zebra leech here that is in question seems to be a common parasite of Meiacanthus kamoharai, although not specific to the species. Others in the same genus appear to be popular hosts, such as M. atrodorsalis, M. grammistes as well as M. anema. The leech we have photographed in this post was one of many that came attached to a shipment of wild caught M. kamoharai. The photo headlining this article shows a coin with a 1.5 cm diameter for size reference.
A quick search reveals several types of leeches, in an assortment of colour and size. It is not known if these parasites are host specific, although it seems the zebra variety are particularly fond of Meiacanthus blennies. The physique is simple, and are very similar to land leeches. A suction cup like mouth part, and another similar structure on its tail end for adhesive purposes.
With any parasite, the most important question is, how do we treat it. Well, we found these leeches to be extremely resistant to most of our treatments, which is unusual for a macro parasite as these are usually easily dislodged. Freshwater dips and praziquantel baths did nothing, as well as acriflavin dips. In the end it was a formalin dip that did the trick. A pretty extreme course of treatment for such a large parasite. Physical removal is not recommended, as it may cause wounds that could be susceptible to infection. Copper or potassium permanganate may be other suitable treatment protocols for leeches.
The next time you encounter one, however unlikely it may be, do not be alarmed. They look scary and gross but the harm they inflict is probably not as much a cause for concern as compared to let’s say, velvet or ich. Just take a few minutes to admire its unorthodox beauty, and they get rid of it with a chemical bath. Too little is known about them, let alone how they reproduce. It is quite unlikely that a reoccurrence will surface after the initial removal of the adults.