identification and treatment for monogenean oncomiracidium fluke on Paracanthurus tang

Peter Houde

Community Member
View Badges
Joined
Feb 28, 2021
Messages
31
Reaction score
8
Location
New Mexico, USA
I would greatly appreciate your advice regarding the identification of and treatment for a "fluke" that has recently infested my tank and Paracanthurus tang.

I have a marine aquarium that is heavily infested with some form of monogeneans. One fish exhibits overt disease ("blue tang", Acanthuridae: Paracanthurus hepatus; probable infestation of cornea, loss of color in facial region, deterioration of dorsal and caudal fins possibly due to secondary infection). Several other fish are seemingly unaffected (including 15-20 yr old clownfish), but a damselfish that permanently lost facial color many years ago may have been harboring parasites all along. It also has some tattering of pectoral and caudal fins, and both it and a mandarin have developed small (<1 mm) unequally sized white spots within the last days since I began treatment (described below). The tang's behavior is normal. It does "twitch" but this seems to be only in response to human proximity/close observation; it does not seem to twitch when observed from a distance and it does not rub or scratch itself on objects. None of the fish do. None of the fish show labored breathing. I am anxious to identify the parasite at least at a taxonomic level that will help me to decide the best method of treatment, both for the fish and the entire aquarium.

Tank: established >25 years; fish only; 473 liters; temperature 78F, 25.5C; specific gravity typically 1.024 (but currently 1.018, please see below); nitrate ca. 15 mg/l; no ammonia or nitrite test but pH 8.15 and NO3 suggest this isn't an issue; no copper test but no conceivable source of copper; phosphate ~0.32 (Hanna spec; lower by Salifert and Reef Master tests); KH/Alk 10.33-10.5 (Salifert; 9-10 by Reef Master); Ca 430 ppm (Salifert: 380 by Reef Master); Mg 1290; biological filtration (bio-balls in sump, 5-6 cm coral gravel, abundant purple coralline algae, and Gracilaria, Chaetomorpha, and Penicillus macros) and protein skimmer. I apologize the image of my aqarium is not a full view but it is representative of the whole tank.
Inhabitants: 2 Amphiprion ocellaris, 1 Chrysiptera parasema, 1 Pseudochromis paccagnellae, 1 Synchiropus splendidus, 1 Paracanthurus hepatus, various snails (cerithiids, Neritina, Nasarius, unidentified), emerald crabs, bristle worms, tube worms, unidentified worms, more bristle worms, unidentified colonial tunicates, unidentified encrusting sponges, amphipods, copepods, and things that mysteriously come and go as if by spontaneous generation - now to include monogeneans.

It is not practical for me to capture the afflicted tang (though I've not ruled out the possibility entirely), so I have not been able to examine adult parasites. I also have not observed eggs. However, oncomiracidia were suddenly frighteningly abundant on the aquarium glass. None can be found still 2 days after water change and glass cleaning, but I refuse to believe that they are not all over the live rock. I check the glass regularly for copepods and I've never seen oncomiracidia before. I recorded a video that is decidedly of better clarity than the attached still photo, but at 139 Mb the video is too large to upload. You can access it if you wish on my server at:

http://lithornis.nmsu.edu/~phoude/oncomiracidium 139 Mb.MOV

There are a few characteristics I can describe. It is at least somewhat shorter and much narrower than an adult copepod, e.g., Tisbe. It is ciliated on what I interpret as its dorsal side. There are very long and pronounced cilia around its anterior end that beat synchronously and continuously and extend deeply into its pharynx or caecum. The caudal-most cilia are also elongate. It has no eye spots and no anchor hooks that I can discern, so I do not believe this is Neobenedenia even if that is the most common scourge of marine aquaria. The oncomiracidia on the glass of the aquarium are considerably more elongate than the one in my image, and they are quite active. Under the microscope they become shorter in length and soon disintegrate, possibly killed by the focused microscope light.

Question: Can you identify this to a level that would assist in determining the best treatment?

Question: I dosed the tank once with praziquantel to a concentration of 2.5 mg/l (on 2021/02/27) given my crude estimate of tank water volume after displacement by gravel and live rock. I've been supplementing frozen food diet (San Fransisco mysis, brine shrimp, and Emerald Entree, and Ocean Nutrition Formula 2) with metronidazole (SeaChem Metroplex) and nitrofurantoin (SeaChem Focus) garlic extract and Brightwell's Aminomega daily for 3-4 weeks. I have read some conflicting information regarding the appropriate dosing of praziquantel that I hope you can arbitrate. Hikari's Prazipro recommends dosing of 2.5 mg/l with the potential for re-dosing in 5-7 days but as early as 3 days, and that seems to be the popular opinion. However, several published references suggest that 2.5 mg/l should be added every 2 days until 10 mg/l is reached. I'd appreciate advice on protocol or alternative treatments.

Question: Reefs.com (Joe Rowlett) advocates reducing salinity to 15 ppt for 5 days (specific gravity 1.011), citing several studies on its effectiveness for treating for Neobenedenia. One of those references specifically found 18 ppt (SG 1.013) ineffective. That frightens me. Is 15 ppt safe for fish? Is it safe for snails, crabs, coralline algae, copepods, etc? (no live corals) Marine Parasites.com provides an interactive tool for scheduling re-dosing (without specifying dosage) based on temperature and salinity; but it makes no distinction of efficacy at different salinities. Regardless, I don't believe I am dealing with Neobenedenia. I have somewhat reluctantly already reduced specific gravity to 1.018 with the aim of continuing to decrease salinity, but only as low as you recommend. Is hyposalinity plus medication more effective, contraindicated, or inconsequential?

Question: What OTC fish anaesthetic is tang safe?

IMG_2461a.JPG DSC_0416a.JPG
 
https://www.youtube.com/c/ReefStache

vetteguy53081

Well known Member and monster tank lover
View Badges
Marketplace Rating
Joined
Aug 11, 2013
Messages
45,267
Reaction score
103,520
Location
Wisconsin-Florida in a year
Looks like the Platyhelminthes known as Schistosoma fluke
PraziPro should beat this fluke
 
OP
P

Peter Houde

Community Member
View Badges
Joined
Feb 28, 2021
Messages
31
Reaction score
8
Location
New Mexico, USA
Yikes! I hope I can't catch it. Snails could explain how this got introduced if they are intermediate hosts of marine schistosomes as they are of freshwater species. Some hitchhikers came in with some new macroalgae recently. The ID is good news I suppose if correct and that it can be reliably treated with prazi. Any thoughts about the efficacy of hyposalinity and its safety for my tank inhabitants?

It seems my tank image did not upload properly in my original post. I'm attaching it to this message for reference. It only shows the middle third of the aquarium but it is fairly representative of what is not visible except that rock/coral skeletons extend vertically nearly to water line to sides out of view.
 

Attachments

  • DSC_0626a.JPG
    DSC_0626a.JPG
    412.6 KB · Views: 10
OP
P

Peter Houde

Community Member
View Badges
Joined
Feb 28, 2021
Messages
31
Reaction score
8
Location
New Mexico, USA
I wrote to various parasitologists and marine veterinarians in the United States, Brazil, Malaysia, Japan, and Australia who had published peer-reviewed studies on monogeneans. Most responded. I have it on good authority that my unknown pest is a ciliate protozoan, not a 'fluke' at all. I was surprised to learn that some of the many hundreds of thousands of different species of ciliates belonging to multiple Classes and even more Orders grow to as much as 4 mm long and are worm-like and active (e.g., Spirostomum). Some are parasitic, many are not. So far, there seems to be little possibility of positively identifying what is in my aquarium, so I don't even know for sure whether these are afflicting my tang or whether they are providing a food source for my mandarin - or both. One thing for sure is that the tang has the facial discoloration one might expect from HLLE as well as fin decay, so something is afflicting it. It's been one week on 2.5 mmg/l praziquantel so far, during which I did three small (5%) water changes with 5.0 mg/l praziquantel to account for degradation (see Thomas et al 2016 PerrJ, DOI 10.7717/peerj.1857). Salinity down to 22.6 ppt (1.017 SG) at 25 C. I've also treated daily frozen fish food with metronidazole, nitrofurantoin, and garlic extract for the past several weeks. The good news is that I haven't lost any tubeworms, snails, crabs, tunicates, copepods or amphipods. The bad news is that the tang hasn't gotten any better. I do hope to be able to trap him out and treat him with a copper-based medication, but that's not a solution for the display tank. I'm hoping Ruby Rally and Kick-Ich will put a dent in whatever may exist in the display tank without killing the good guys. I haven't started that treatment yet. This is proving to be an educational experience, one that is still far from over.
 

hds4216

Valuable Member
View Badges
Joined
Jun 18, 2020
Messages
1,253
Reaction score
1,733
Location
Denver, CO
I wrote to various parasitologists and marine veterinarians in the United States, Brazil, Malaysia, Japan, and Australia who had published peer-reviewed studies on monogeneans. Most responded. I have it on good authority that my unknown pest is a ciliate protozoan, not a 'fluke' at all. I was surprised to learn that some of the many hundreds of thousands of different species of ciliates belonging to multiple Classes and even more Orders grow to as much as 4 mm long and are worm-like and active (e.g., Spirostomum). Some are parasitic, many are not. So far, there seems to be little possibility of positively identifying what is in my aquarium, so I don't even know for sure whether these are afflicting my tang or whether they are providing a food source for my mandarin - or both. One thing for sure is that the tang has the facial discoloration one might expect from HLLE as well as fin decay, so something is afflicting it. It's been one week on 2.5 mmg/l praziquantel so far, during which I did three small (5%) water changes with 5.0 mg/l praziquantel to account for degradation (see Thomas et al 2016 PerrJ, DOI 10.7717/peerj.1857). Salinity down to 22.6 ppt (1.017 SG) at 25 C. I've also treated daily frozen fish food with metronidazole, nitrofurantoin, and garlic extract for the past several weeks. The good news is that I haven't lost any tubeworms, snails, crabs, tunicates, copepods or amphipods. The bad news is that the tang hasn't gotten any better. I do hope to be able to trap him out and treat him with a copper-based medication, but that's not a solution for the display tank. I'm hoping Ruby Rally and Kick-Ich will put a dent in whatever may exist in the display tank without killing the good guys. I haven't started that treatment yet. This is proving to be an educational experience, one that is still far from over.
Based on an initial glance, I was very suspicious that this was a Schistosoma. I am not an expert on the subject, but some basic research revealed several problems with that theory. Great job with the thorough research. Many times I have seen some reefers on this forum misidentify things. It is often better not to say anything than to give a wrong answer.

Regarding the kick ich, there is no compelling evidence imo that it does anything useful. It is really up to the manufacturer to provide evidence of it working, and the haven't.
 
Top Shelf Aquatics
OP
P

Peter Houde

Community Member
View Badges
Joined
Feb 28, 2021
Messages
31
Reaction score
8
Location
New Mexico, USA
Based on an initial glance, I was very suspicious that this was a Schistosoma. I am not an expert on the subject, but some basic research revealed several problems with that theory. Great job with the thorough research. Many times I have seen some reefers on this forum misidentify things. It is often better not to say anything than to give a wrong answer.

Regarding the kick ich, there is no compelling evidence imo that it does anything useful. It is really up to the manufacturer to provide evidence of it working, and the haven't.
In case anyone is interested, I finally got the answer - and it is GOOD NEWS! They're not parasitic. Here's the letter I received this morning from the Institute of Parasitology (https://www.paru.cas.cz/en/sections/aquatic-parasitology/laboratory-of-fish-protistology/):

Dear Peter,

our colleague, Peter Vdacny, from University of Bratislava, Slovakia, determined this ciliate to family Pseudokeronopsidae, exact species determination is impossible without more details. Peter Vdacny, in his recent paper studied this group of protists.

(Tengyue Zhang, Yurui Wang, Ting Cheng, Jiyang Ma, Peter Vdacny, Weibo Song and Chen Shao. 2020. Systematics and Multi-Gene Phylogeny of the Subfamily Nothoholostichinae (Ciliophora, Hypotrichia), With Integrative Description of a New Marine Species Nothoholosticha luporinii n. sp. Frontiers in Marine Science. doi: 10.3389/fmars.2020.610886)

This group of ciliates is not parasitic one.

Best regards

Ivan
 

Attachments

  • Zhang et al 2020 Systematics and Multi-Gene Phylogeny of the Subfamily Nothoholostichinae (Cil...pdf
    18.4 MB · Views: 2
OP
P

Peter Houde

Community Member
View Badges
Joined
Feb 28, 2021
Messages
31
Reaction score
8
Location
New Mexico, USA
I would greatly appreciate your advice regarding the identification of and treatment for a "fluke" that has recently infested my tank and Paracanthurus tang.

I have a marine aquarium that is heavily infested with some form of monogeneans. One fish exhibits overt disease ("blue tang", Acanthuridae: Paracanthurus hepatus; probable infestation of cornea, loss of color in facial region, deterioration of dorsal and caudal fins possibly due to secondary infection). Several other fish are seemingly unaffected (including 15-20 yr old clownfish), but a damselfish that permanently lost facial color many years ago may have been harboring parasites all along. It also has some tattering of pectoral and caudal fins, and both it and a mandarin have developed small (<1 mm) unequally sized white spots within the last days since I began treatment (described below). The tang's behavior is normal. It does "twitch" but this seems to be only in response to human proximity/close observation; it does not seem to twitch when observed from a distance and it does not rub or scratch itself on objects. None of the fish do. None of the fish show labored breathing. I am anxious to identify the parasite at least at a taxonomic level that will help me to decide the best method of treatment, both for the fish and the entire aquarium.

Tank: established >25 years; fish only; 473 liters; temperature 78F, 25.5C; specific gravity typically 1.024 (but currently 1.018, please see below); nitrate ca. 15 mg/l; no ammonia or nitrite test but pH 8.15 and NO3 suggest this isn't an issue; no copper test but no conceivable source of copper; phosphate ~0.32 (Hanna spec; lower by Salifert and Reef Master tests); KH/Alk 10.33-10.5 (Salifert; 9-10 by Reef Master); Ca 430 ppm (Salifert: 380 by Reef Master); Mg 1290; biological filtration (bio-balls in sump, 5-6 cm coral gravel, abundant purple coralline algae, and Gracilaria, Chaetomorpha, and Penicillus macros) and protein skimmer. I apologize the image of my aqarium is not a full view but it is representative of the whole tank.
Inhabitants: 2 Amphiprion ocellaris, 1 Chrysiptera parasema, 1 Pseudochromis paccagnellae, 1 Synchiropus splendidus, 1 Paracanthurus hepatus, various snails (cerithiids, Neritina, Nasarius, unidentified), emerald crabs, bristle worms, tube worms, unidentified worms, more bristle worms, unidentified colonial tunicates, unidentified encrusting sponges, amphipods, copepods, and things that mysteriously come and go as if by spontaneous generation - now to include monogeneans.

It is not practical for me to capture the afflicted tang (though I've not ruled out the possibility entirely), so I have not been able to examine adult parasites. I also have not observed eggs. However, oncomiracidia were suddenly frighteningly abundant on the aquarium glass. None can be found still 2 days after water change and glass cleaning, but I refuse to believe that they are not all over the live rock. I check the glass regularly for copepods and I've never seen oncomiracidia before. I recorded a video that is decidedly of better clarity than the attached still photo, but at 139 Mb the video is too large to upload. You can access it if you wish on my server at:

http://lithornis.nmsu.edu/~phoude/oncomiracidium 139 Mb.MOV

There are a few characteristics I can describe. It is at least somewhat shorter and much narrower than an adult copepod, e.g., Tisbe. It is ciliated on what I interpret as its dorsal side. There are very long and pronounced cilia around its anterior end that beat synchronously and continuously and extend deeply into its pharynx or caecum. The caudal-most cilia are also elongate. It has no eye spots and no anchor hooks that I can discern, so I do not believe this is Neobenedenia even if that is the most common scourge of marine aquaria. The oncomiracidia on the glass of the aquarium are considerably more elongate than the one in my image, and they are quite active. Under the microscope they become shorter in length and soon disintegrate, possibly killed by the focused microscope light.

Question: Can you identify this to a level that would assist in determining the best treatment?

Question: I dosed the tank once with praziquantel to a concentration of 2.5 mg/l (on 2021/02/27) given my crude estimate of tank water volume after displacement by gravel and live rock. I've been supplementing frozen food diet (San Fransisco mysis, brine shrimp, and Emerald Entree, and Ocean Nutrition Formula 2) with metronidazole (SeaChem Metroplex) and nitrofurantoin (SeaChem Focus) garlic extract and Brightwell's Aminomega daily for 3-4 weeks. I have read some conflicting information regarding the appropriate dosing of praziquantel that I hope you can arbitrate. Hikari's Prazipro recommends dosing of 2.5 mg/l with the potential for re-dosing in 5-7 days but as early as 3 days, and that seems to be the popular opinion. However, several published references suggest that 2.5 mg/l should be added every 2 days until 10 mg/l is reached. I'd appreciate advice on protocol or alternative treatments.

Question: Reefs.com (Joe Rowlett) advocates reducing salinity to 15 ppt for 5 days (specific gravity 1.011), citing several studies on its effectiveness for treating for Neobenedenia. One of those references specifically found 18 ppt (SG 1.013) ineffective. That frightens me. Is 15 ppt safe for fish? Is it safe for snails, crabs, coralline algae, copepods, etc? (no live corals) Marine Parasites.com provides an interactive tool for scheduling re-dosing (without specifying dosage) based on temperature and salinity; but it makes no distinction of efficacy at different salinities. Regardless, I don't believe I am dealing with Neobenedenia. I have somewhat reluctantly already reduced specific gravity to 1.018 with the aim of continuing to decrease salinity, but only as low as you recommend. Is hyposalinity plus medication more effective, contraindicated, or inconsequential?

Question: What OTC fish anaesthetic is tang safe?

IMG_2461a.JPG DSC_0416a.JPG
For anyone interested, these turned out not to be flukes at all; rather, non-parasitic giant worm-like protozoans (see thread below). And like so many other things, they eventually disappeared as mysteriously as they arrived.
 

HAVE YOU EVER BUILT A NEW HOUSE "AROUND" A NEW DREAM REEF TANK SET UP?

  • Yes (tell us in the thread)

    Votes: 50 14.2%
  • NO, but I would like to

    Votes: 220 62.7%
  • NO, I would worry about the tank later

    Votes: 70 19.9%
  • Other (please explain)

    Votes: 11 3.1%
Chaos Aquaculture
Top