Black "Ich", Black Spot, Turbellarian Infection
While Black "Ich" is not all that common, it is not uncommon either and appears from time to time, particularly on tangs and surgeonfish.
What causes black "Ich"??
Black "Ich" is caused by one or more genus of flatworm (Phylum Platyhelminthes) belonging to the class Turbellaria. Most cases of black "Ich" appear to be caused by
Paravortex sp. (Noga, 2000) however, Cannon and Lester (1988) found turbellaria of the genus
Ichthyophaga on a parrotfish (
Scarus ribulatus) in addition to
Paravortex sp. on dusky flathead (
Platycephalus fuscus).
The life cycle of Paravortex sp.
Noga (2000) describes the life cycle of the parasite as follows. Juvenile turbellaria attach to the host fish and grow from around 77 to 450 μm. After around 6 days, they drop off the host and fall to the substrate where their eggs and larvae develop internally for 3 to 4 days. The adult's body wall ruptures and up to 160 juveniles escape and can immediately infect any susceptible hosts. The life cycle takes around 10 days at 24.5?C (76?F).
The signs of black "Ich"
The most obvious sign of black "Ich" are numerous dark spots covering the body of the infected fish. The dark spots are not the turbellaria but rather a reaction of the skin to the parasite which causes hypermelanisation (Noga, 2000).
Treatment for black "Ich"
Noga (2002) recommends
formalin baths for the treatment of parasitic turbellaria. The formalin baths should be repeated every three days until there are no signs of infection. With this regime subsequent baths will kill parasites that were not on the fish during previous baths.
Some hobbyists have had success with the use of
freshwater dips. These should also be repeated at 3 day
Turbellarian Infection
This infection is seen most often on Yellow tangs, partially because the black spots are so easily visible against a yellow background. These parasites are known to infect at least 16 tropical marine fish species. Usually, only one or two fish are affected. Some common names are Tang Disease and Black Ich.
Symptoms to look for are as follow:
? Black spots on the skin with a pepper-like appearance
? Scratching
? Faded colors
? Hyperactivity
? Decreased appetite
? Lethargy in advanced stages
? Increased respiration in advanced stages
? Skin hemorrhaging in late stages
? Secondary bacterial infection, which may include cloudy eyes and fin rot in
late stages
