What You Need To Know:
* Ciliated protozoan parasite that is not usually problematic unless the potential host(s) are weakened, diseased or being housed in a system with poor water quality.
* Symptoms are mostly behavioral: Scratching/flashing, clamped fins, heavy breathing. Heavy infections of Trichodina can cause a greyish, white film over the body of the fish.
* Easily killed when exposed to copper, formalin, or a 5 minute freshwater dip.
There are about 70 marine species of Trichodina. They reproduce by simple binary fission (each cell splits into two), are host specific (no encysted stage), and spread via incidental contact with the host fish. (Although it is also possible for the organism to be free-floating in the water column.) They are sometimes called “Flying saucers”, because of their resemblance under a microscope. Trichodina spp. typically target the gills, skin and fins of fishes, though some species parasitize the urogenital system.
A range of invertebrates are also host to trichodinid infections, including the surfaces of copepods and the mantle cavity of molluscs and snails. Transmission of these occurs by direct contact of infected and uninfected hosts, and also by active swimming of trichodinids from one host to another. When on a fish, the organism feeds off any bacteria it finds and causes the fish irritation. There is no fallow period for Trichodina because the organism can subsist off bacteria; pretty much every tank will eventually get these parasites (through inverts)!!
The good news is that most species of Trichodina are nonpathogenic and even the harmful ones are usually only a problem for weakened fish being housed in poor conditions. (Poor water quality usually means high bacterial count which provides a source of food for this parasite and so leads to high numbers of the parasite.) Fish are typically resistant to Trichodina when provided a low stress environment, good water quality and a nutritious diet. Fish may recover without treatment when provided with improved water conditions.