【アクアリウム/コリドラス水槽】今はこの方法で駆除するしかない！～またもやギロダクチルスかダクチロギロダクチルスのどちらかがコリドラスに寄生、再び高濃度塩水浴で駆除する/海水魚は淡水浴で寄生虫を駆除

When I checked the footage I took when making my last video, I found that my Corydoras had a parasite that looked like Gyrodactylus again, for the second time. I was planning to get rid of it right away, but before I could, my Corydoras Panda and Adolfoy died. I'm very sad about this, and at the same time, I feel responsible. I don't know what caused these two to die, but I don't think it was due to parasites. The last time, almost three months ago, my Corydoras sterbai died from Gyrodactylus parasites, and it was covered in a huge amount of Gyrodactylus and it was obvious that it was sick. Actually, I only noticed something was wrong when I checked the video of it after it died, but this time, although it was parasitized, it wasn't in such a bad condition, and in fact, I couldn't find any evidence of Gyrodactylus parasites on these two. A few weeks ago, I moved 12 Corydoras from a soil and aquatic plants tank to a simple tank with sand. However, since I had filled the new tank with water from another tank when setting it up, I moved the Corydoras into the new tank fairly soon after setting it up. Although it's not visible to the naked eye, I think the deterioration in water quality may have caused some damage to the Corydoras. Of course, there are organic matter decomposing bacteria and nitrifying bacteria in the tank, but they don't settle immediately, and nitrifying bacteria in particular settle in a biofilm, so this isn't the case immediately after setting it up. Under these conditions, I was adding large amounts of newly procured food at least twice a day, but I think there may have been a delay in the decomposition of the organic matter. When I cleaned the filter this time, the sponge was very dirty. Of course, this is partly due to the small size of the filter, but I was surprised it would get that dirty in just 15 days. In any case, the conditions in the aquarium are not good, and if the Corydoras are infested with Gyrodactylus under these circumstances, there is a risk of further casualties. Therefore, in order to respond quickly, we will first eliminate the Gyrodactylus parasite with a high-concentration salt bath. As we have covered in previous videos, the method is the same: place the Corydoras in 2% salt water for 15 minutes to eliminate the parasite. The Gyrodactylus, which is suspected to be infesting the Corydoras in this case, is an ectoparasite classified as a monogenean flatworm. There are many different types, with more than 10 known to infest carp alone. There is also a species similar to Gyrodactylus called Dactylogyrus, and both parasitize the fish's body using hooked suction cups and feed on mucous membranes and epithelial cells. Gyrodactylus is 0.2-0.8mm in size, while Dactylogyrus is around 0.8-2mm, and as the parasite in this case is not visible to the naked eye, I believe it is probably the former, Gyrodactylus. It attaches to the fish's body and stretches and contracts, but unlike anchor worms, it can move on top of the fish. Gyrodactylus and Dactylogyrus look very similar, but they also have some significant differences. Gyrodactylus is viviparous, giving birth to larvae that are the same shape as the parents, but it seems that these larvae can sometimes develop into offspring, which is why Gyrodactylus is called a third-generation insect. Gyrodactylus reproduces by giving birth to offspring one after another on the surface of a single carp's body, so it is possible for a single Gyrodactylus to develop in just one carp in a school of carp. Dactylogyrus, on the other hand, reproduces by laying eggs. It is not clear whether the same species that parasitize carp also parasitize Corydoras, but Gyrodactylus that parasitize carp are more likely to occur during the low water temperatures of autumn and spring, while Dactylogyrus are more likely to occur during the high water temperatures of spring and summer. They appear and become a problem when the water quality deteriorates, and this Corydoras tank is always kept at 26°C. Based on this information, I would think that Dactylogyrus is a parasite that appears during high water temperatures, but it has recently been said that Gyrodactylus can also appear in high water temperatures. Furthermore, Dactylogyrus often parasitize the gills, while Gyrodactylus is said to parasitize the gills, body surface, and fins. Based on this information, it is highly likely that the Gyrodactylus that parasitizes Corydoras is also a parasite that appears on the body surface. As I mentioned at the beginning, about three months ago, most of the Corydoras I was raising became infested with Gyrodactylus, which I eradicated with a high-concentration salt bath at the time. I then purchased four new Corydoras from the same pet shop and put them in the same tank as the existing ones. I think it's highly likely that these newly introduced Corydoras brought the Gyrodactylus with them, but Shiga Prefecture's published results for eradicating Gyrodactyl...