Black Ich (turbellarians)

[Fishfinder]

So is the best treatment as of now a formalin dip? Is there is any validity to fish dying sooner due to exposure to formalin? @Jay Hemdal

 

[Jay Hemdal Verified Community Expert]

So is the best treatment as of now a formalin dip? Is there is any validity to fish dying sooner due to exposure to formalin? @Jay Hemdal

The trouble with formalin is that it is a known human carcinogen, and really must not be used inside a home. That said, all that you might hear about formalin causing latent mortality in fish is totally unfounded. Fish can be exposed to it from the egg stage (as in trout hatcheries) through adult stage without showing mortality from it later on.

The safest treatment would be a 5 to 7 minute FW dip and then moving to a clean tank. This process would then most likely need to be repeated two more times.

Here is an excerpt from a book I'm working on about this:

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 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 a 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. There is a digenean trematode that causes similar lesions, Scaphanocephalus and related genera. These produce more diffuse black spots (often on surgeonfish) and because of their complicated life cycles, do not need to be treated as the disease won’t progress without secondary and tertiary hosts.


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 trematode worms, but despite being “prescribed” by many people, it is not very effective for turbellarians. Praziquantel doesn’t kill worms, it just causes them to relax their grip and let go of the fish. These turbellarians are beneath the skin, so do not drop off easily when exposed to praziquantel.

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 to 20 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.

A freshwater dip. for five to seven minutes, followed by moving the affected fish to a non-infected tank is moderately effective at treating encysted turbellarians. The process may need to be repeated a total of three times, every five days.

 

[Fishfinder]

I’ll probably coin toss between the fresh water and formalin

 

[Ironwill723]

@Jay Hemdal could you expand on this old article you wrote regarding chloroquine phosphate usage for turbellarians at the Georgia Aquarium. I also see you mentioned its use in the excerpt from your new book. What is the standard length (hours or days?) of treatment with chloroquine for turbellarians? Is a simple 24 hour bath enough or is a longer exposure to CP needed? I have already tried hypo for 30 days, prazi, and formalin methods but I am dealing with a stubborn strain.

 

[Jay Hemdal Verified Community Expert]

@Jay Hemdal could you expand on this old article you wrote regarding chloroquine phosphate usage for turbellarians at the Georgia Aquarium. I also see you mentioned its use in the excerpt from your new book. What is the standard length (hours or days?) of treatment with chloroquine for turbellarians? Is a simple 24 hour bath enough or is a longer exposure to CP needed? I have already tried hypo for 30 days, prazi, and formalin methods but I am dealing with a stubborn strain.

The 10mg / liter would have been a static bath - probably 14 days, maybe a bit longer. I don’t know if the chloroquine they used killed the encysted adults, or the infective juvenile stage, so a “dip and move” probably isn’t going to work.

Not all black ich is caused by the same organism - some spots are caused by deeply encysted digenean trematodes. Those resist all treatment, but they require secondary hosts, so they do not perpetuate in aquariums. I’m also not sure that some spots that we see aren’t granulation tissue from previous infections (scars if you will).

 

[Ironwill723]

The 10mg / liter would have been a static bath - probably 14 days, maybe a bit longer. I don’t know if the chloroquine they used killed the encysted adults, or the infective juvenile stage, so a “dip and move” probably isn’t going to work.

Not all black ich is caused by the same organism - some spots are caused by deeply encysted digenean trematodes. Those resist all treatment, but they require secondary hosts, so they do not perpetuate in aquariums. I’m also not sure that some spots that we see aren’t granulation tissue from previous infections (scars if you will).

Thank you @Jay Hemdal . In your experience is a single dosage of CP at 10-15mg/l for 14 days sufficient or should it be repeated every X amount of days?

 

[Jay Hemdal Verified Community Expert]

Thank you @Jay Hemdal . In your experience is a single dosage of CP at 10-15mg/l for 14 days sufficient or should it be repeated every X amount of days?

It is degraded by bacteria like prazi is, but the initial dose can last up to 30 days. Since there is no way to measure it (unless you have access to a UV spectrophotometer) the only way to safely redose it is to change the water with a new full dose added.

 

[Ironwill723]

It is degraded by bacteria like prazi is, but the initial dose can last up to 30 days. Since there is no way to measure it (unless you have access to a UV spectrophotometer) the only way to safely redose it is to change the water with a new full dose added.

@Jay Hemdal these fish (3 x tangs, 1 x rabbitfish, 1 x clownfish) would be coming out of a 20 year old large 300g reef display that is being replaced by a new larger 400g display aquarium. The reason I asked about treatment duration is because the fish will be temporarily housed in a large stock tank while the livestock and tank contents are being switched over to the larger tank. I am trying to come up with the best game plan to not to transfer over the turbellarians which came in on a new QTd fish about a year ago.

 

[edyta23]

This was more of an informative post that would be used as a reference or a place to ask "black ick" related questions. But I think I can answer your question anyway. After two rounds of Prazipro a week apart, with a water change in between the fish would have been cleared of the worms. The first round of Prazi will kill the adults but not the eggs left behind. The second round kills the newly hatched babies before they can lay more. The water change in between will help dilute any pollution (minimal) caused by all the dying worms.

Prazi is only active in the water for 48 hours and only takes 24 hours to work its magic. I hope this answers your question, if not please feel free to clarify what you were looking to find out. :)

What about fluke solve as in the uk can’t get prazi