Those are just sample photos? Are any of your fish specifically? The first image isn't clear to me, but the others all look like "Black ich" a turbellarian worm.
Here is an excerpt from my upcoming book about that:
Turbellarian Infection (a.k.a. black spot disease, black ich, tang disease)
Turbellarians are a group of worms related to trematodes. They often go undiagnosed as a cause of active infections in fishes except for one group: Paravortex sp.
Cause and symptoms
Since this disease is often seen in newly acquired fish, the suspicion is that the fish bring the disease with them and become infected due to the transport stress they endure.
This parasite causes very distinctive black spots on some species of fish, most notably tangs and surgeonfish. Other fish that may become infected with Paravortex include butterflyfishes, angelfishes, gobies, and jawfishes.
The worm encysts under the fish’s skin, and the fish deposits black melanin pigment as a reaction to the infection. Since these spots are so apparent to even the casual observer, this disease is easily diagnosed, even by beginning aquarists.
Often self-limiting
The problem is that this sometimes causes the aquarist to overreact and begin a treatment that actually might be more harmful than the disease itself. It turns out that many cases of Paravortex infections are self-limiting; unless tank conditions are very poor, the worms often die out and the infection goes away on its own.
Only if the spots increase greatly in number (more than 20 spots on a fish) or the fish begin showing other signs of ill health should a treatment be undertaken.
Cleanliness counts
Some aquarists have reported that careful siphon-cleaning of the aquarium substrate and improving overall cleanliness in the aquarium helps to reduce this infection. It is possible that Paravortex has a non-parasitic, free-living form at one stage of its life cycle and that careful cleaning will remove the parasite at that point.
Some turbellarians are tougher to diagnosis
There are other turbellarians that do not cause melanistic skin changes in fish and are much more difficult to diagnose. Ichthyophaga is one type known to infect fishes and can cause significant fish loss in crowded conditions. Diagnosis of this parasite generally requires a skin scrape.
It’s also noteworthy that treatment with freshwater dips may contort the worm’s body shape so much that positive identification is difficult. In some cases, no real symptoms are seen until fish loss occurs. Under the microscope, look for an oval-shaped worm with a pair of dark eyespots.
Treatment options
Because turbellarians cause a fairly deep-seated infection, they are difficult to remove using freshwater dips or other topical treatments. Other treatment options that have been utilized with varying degrees of effectiveness include:
● Praziquantel at 2 mg/l is a safe, commonly used treatment for this malady, but for some reason, it is not always effective.
● A 45-minute formalin dip at 166 ppm can be effective, but then the fish must be moved to a non-infected aquarium.
● Chloroquine at 15 ppm has been shown to be an effective treatment, but some fish may experience toxic reactions at this dose.
● Organophosphate pesticides, such as Trichlorfon (Dylox), have been the treatment of choice for many years but cannot be recommended due to their potential toxicity to humans.
● Copper treatments are ineffective, at least at the concentrations well tolerated by fish.
Jay
