Tangs and black "ick"

[Fishtail]

So glad to have a place to ask questions.
My tangs seem to have black ick. I understand that 2 doses of PraziPro, 7 days apart is the treatment protocol . My questions are can I/should I treat in the display tank? Will prazi harm my mushrooms, pistol and cleaner shrimp, snails and crabs? What is the lifecycle of the worm? Might I have eggs in the DT that other fish may attract.
Background-
The tank is 140 gallons that is 10 months old. Temp range is 77.5-78.4. pH is 8-8.4, Nitrates are at 9.8, and Phos is at .05.
We had an out break of ick/velvet on Aug 13 2022 and QT ed and treated all fish in copper, general cure, metro. We lost all but 3 fish. The tank was fallow for 81 days.
New fish were bought online and sold as quarantined fish. the protocol was 2 weeks in copper 1.75-2.25., moved to new tank, prazipro and metro every 3 to 5 days, and feed bendazole with metro, for 2 more weeks.
Once they arrived I observed them for 7 more days in a QT tank. They have been in the DT for 30 days. All inverts and corals have been qt ed for 45 days.
Stock List- Purple tang, Powder Blue, Hippo, Blue Eyed kole (all have slightly bumpy spots). Wrasse McCosker, orange shoulder, Yellow coris (damaged scales). 2 shotgun clowns, Gobies, yellow watchman, sand sifting, aptisia eating file fish. 2 cleaner shrimp, 1 pistol, 2 conch, 2 emerald crabs, 3 types of snails.
I would like to treat in the tank because our last fallow period was a nightmare. What am I risking?

 

[Jay Hemdal]

Praziquantel is essentially reef safe if dosed accurately and good aeration is supplied. However, "black ich" is caused by one of two species of turbellarian worm that live in a cyst. Praziquantel acts by paralyzing the fluke so that it drops off. At least one of those worms will not fall off when exposed to prazi....I'm not sure of the other.

That said, can you get clearer photos? I can't confirm the diagnosis from that one.

Here is an excerpt from my book about this:

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

 

[vetteguy53081]

Cant see it in pics but treatment of choice is PraziPro and while reef safe I prefer QT tank for treating but not necessary. If in dislay tank, remove your skimmer cup but leave the skimmer running as prazi-pro will make your skimmer go nuts. It will produce a truly amazing amount of bubbles so still have your skimmer running to keep the oxygen levels high in the water as some medications like praz-pro can lower the amount of oxygen in the water which is something you want to avoid so I recommend running an airstone in addition to treatment. The concern I have is the survival of any in display tank which will seek another host fish as these are turbellarian worms
Also . . . remove any type of carbon that you have running to allow Prazi to run at full strength which will be 8 day interval, change water and treat again for one more 8 day interval.

 

[Fishtail]

"Black Ich" (I can't believe I titled the thread incorrectly.)
Thank you so much for the wealth of information. I was able to catch the hippo today. (He swam into the acclamation box.)

The black spots are for the most part gone. I'm assuming the worms have fallen off and are now continuing their lifecycle in the tank. Just the white patches remain. (The fish was breathing normally until trapped, now it's swimming hard into the corners trying to escape.) The powder blue's side scales simply appear a little ruffled/bumpy. The purple looks fantastic.