Monogenean Parasites, Marine Fish
Coral reef fish harbor an unexpectedly high biodiversity of parasites
In the same way as the tropical rainforest, the coral reefs of warm seas are among the richest ecosystems of the world in terms of their biodiversity. In fact the best conserved areas harbor over 700 species of coral, 600 species of mollusk and nearly 4000 species of fish. These fish have been well studied by reef biodiversity specialists over the past few years, yet still little is known about their parasites. Two studies conducted by IRD researchers of Noumea have brought out evidence of this parasite species richness in two grouper species of the New Caledonian coral reef.
This is a good reason to quarantine your new arrivals to your marine tank and find a good source for your saltwater fish and stick with it. This also speaks for other prevention methods including but not limited to UV Sterilization via a properly installed UV Sterilizer (if a UV Sterilizer is employed for Redox control and disease prevention, it is imperative to change your UV Bulb every six months for maximum effectiveness!!).
If a quarantine tank is not available, a 30 minute bath (in a dark location) using Methylene Blue or for a stronger bath (especially if Flukes are suspected) Potassium Permanganate followed by a 3-5 minute dip in pH, KH adjusted freshwater is a viable option for prevention.
For in tank or in pond treatment either Potassium Permanganate or Quick Cure are viable options, although not always 100% and quite expensive for a pond.
What are Monogeneans?
Monogeneans (flukes) are a group of parasites best described as flatworms. Monogeneans are commonly found on the gills, skin or fins of fishes and lower aquatic invertebrates. A few may invade the rectal cavity, ureter, body cavity and even the blood vascular system. There are more than 100 families of Monogeneans found on fishes of the world, in fresh and salt water, and at a variety of temperatures.
Most Monogeneans are browsers, moving about the body surface and feeding on dermal (skin) mucus and gill debris. Monogeneans have a series of hooks that enable them to attach while feeding. Most species are host- and site-specific, requiring only one host to complete an entire life cycle. In fact, some adult Monogeneans will remain permanently attached to a single site on the host.
Morbidity and mortality epidemics in cultured fish caused by excessive parasite loads are associated with crowding, inadequate sanitation and deterioration of water quality. Although Monogeneans are commonly found on wild fish, they are rarely a direct cause of disease or death in free-ranging populations.
Freshwater fish infested with skin-inhabiting flukes become lethargic, swim near the surface, seek the sides of the pond and their appetite dwindles. They may be seen rubbing the bottom or sides of the holding facility (flashing). The skin, where the flukes are attached, shows areas of scale loss and may ooze a pinkish serous fluid. Heavy gill infestations result in respiratory disease. Gills may be swollen and pale, respiration rate may be increased, and fish will be less tolerant of low oxygen conditions. "Piping," gulping air at the water surface, may be observed in fish with severe respiratory distress. Large numbers of Monogeneans on either the skin or gills may result in significant damage and mortality. Secondary infection by bacteria and fungus is common on tissue that has been damaged by Monogeneans.
In salt water fish, sharks, skates and rays, the Monogeneans, Neobenedinia spp., may infest the skin and gills, resulting in extreme irritation to the host. Sharks with heavy infestations swim erratically, and exhibit behavior such as flashing and rubbing on the bottom of the tank. Gray patches and open wounds may appear on the skin. Ulcerated skin lesions are susceptible to secondary bacterial infections, which may result in mortality. Affected gills may become irritated, hemorrhaged and swollen. Sand grains may stick to the gills as infested sharks suck in sand in an attempt to rub off the parasites.
Much of the information provided here comes from this source (which I recommend for further reading): Monogenean Parasites of Fish.
I also recommend this article from Aquarium Answers: Trematodes and Nematodes in Fish.
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