Gerald Bassleer examines a halfbeak with tiny black specks on its skin, revealed under the microscope to be encapsulated parasitic worm larvae. The fish hangs at the surface and rarely feeds. High-salinity baths may help, but the prognosis is poor because the larvae are protected inside capsules.
Questions this video answers
Dermogenys pusilla borealis
Metacercaria (encysted larval stage of digenetic trematodes)
Approximately 10 grams of sea salt per liter for at least 30 minutes; may be repeated (e.g., twice a week)
Case #67; video created/uploaded January 18, 2023
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Dear aquarist, today, another case of a special tropical accordion fish, which some people like a lot and it's coming from the wild. And of course then we might expect also some wild diseases that we found when we do examination. So in this case 67, we will talk about a half beak. Scientific name is the Dermagenis pusilla borealis, which was infected with Metasercaria. Those are worm larvae from the digenetic trematodes. I show you my findings during my observation and use of my microscope. Here we see them swimming in the water. You see them swimming very regular, upside down, dying. And with the naked eye it's very difficult to do identification of a specific disease. You see them that's typical, the behavior of the half beak hanging at the surface because they are a surface eater and eating small insects floating on the water and some leftover food. And here we have another observation of the fish in the tank. You might spot on a few of them, show you that a few black specks can be noticed inside of the body of the of those half beaks. I tell you, it's very difficult just to see when you see them swimming in into the water. But we notice some little black spots here. You might see it a little bit more clearly, but still it's very small, it's tiny, it's microscopical. That's why we take a microscope when we taking a skin scraping. And that's what we found on the skin you see the few scales and in the mucus, you see here some encapsulated worm larvae. You see them here slowly moving around. And we took another part of the scraping. You see quite a few more here. They come out of the capsule here. 1, 2, 3, 4, 5. There were plenty of them, many worm larvae sitting on the skin on the scales of this half beak. And this worm eventually will be eaten by, by a bird, by another big predator fish. And then the worm eating together with the fish that will develop into an adult worm. That's the Metas ricardia, that's the larval stage. So what can you do here for this fish? Well, unfortunately the badly infected have beaks, will soon die because they cannot survive with such a load of parasites. And those while they will also show secondary infections and weaken quickly, particularly bacterial infections are coming up quickly or they're starving, they're not eating well. That's the problem with this kind of infections. And there is no real effective treatment available to kill those worm larvae because they're usually in a capsule. We had some suggestions and trials on the high salinity baths, salt salt baths of 10 gram of sea salt per liter during at least 30 minutes, a half an hour. And that can kill or at least destroy some of the worm larvae. You can try that maybe two times a week. It might be effective. It's worth trying to better than doing nothing. So it's something worthwhile to think about. You can try anti worm medications on do it, but it's difficult for the product to enter to the encapsulated worm larvae. So this is a specific case we deal with when we having wild fish. You know, that's wild fish is something that brings in specific interesting diseases. For me as a pathologist, I always love to see wild fish because they give me opportunities to see something very unusable in our fish disease things. So stay tuned. I will show you some more interesting things in the coming weeks.
