Flukes

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Humblefish

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Flukes (Monogeneans) – General Guidelines

Many thanks to “Newsmyrna80” for writing this. Reposted with her permission.

Some facts:
Flukes are not true flukes. They are actually parasitic flatworms belonging to the class of Monogeans.

There are 13 families of flukes. However, only three families infect saltwater fish.
1. Ancyrocephalidae – common to freshwater, brackish and marine fish. They have 14 hooks which insert into the fish’s skin to maintain contact. They are oviviparous (egg layer). They are not host specific and they prefer the fish’s gills and esophagus.
2. Gyrodactylidae – common in freshwater but can be found on saltwater fish. They have 16 hooks and are viviparous (live bearing). This family of flukes is considered “Russian dolls” meaning that a live daughter is inside the mother and the live daughter can also be carrying a live daughter.
3. Capsalidae – common in saltwater fish. They have 2 hooks and are oviviparous. The most common genus of Capsalid found in saltwater aquaria is the Neobenedenia. It is host specific, attacking angelfish, butterflyfish, and elasmobranchs, to name a few targets and location specific (face, lips, and eyes). However, if a fish has an extensive infestation the fluke will find somewhere else on the body to host.

Luckily for aquarists, the life cycle of flukes has been researched due their ill effects on aquaculture farming and the fishing industry. Extensive studies have been done on Neobenedenia, the most common in saltwater aquaria.

Life Cycle

At 78-79° F eggs hatch within 4-6 days. Once the egg hatches the oncomiridium (ciliated larva) finds a host and crawls on the body to their preferred site. Once they dig their hooks into the fish’s flesh they feed on it for 17-19 days. At that point it has matured to an adult and it begins to lay eggs. The cycle starts over. At lower water temperatures, 34-36°F the timeline can extend to 5-6 months.

Symptoms

Fish can become lethargic, swim near the water surface, develop clamped fins, hide in the corner of the aquarium or behind rocks, lose appetite, shake the head, flash, or scratch. They may exhibit yawning, cloudy eyes and loss of color at the insertion site. For example, Neobenedenia prefers the face, lips and eyes; therefore you may notice the skin color faded in those areas. If flukes are present in the gills they may be swollen and pale, increase respiration, and begin piping (gulping air at the water surface). Fish generally become less tolerant of low oxygen conditions. Secondary infections are also very common. Some fish may not show any symptoms at all which is why quarantining is so important.

Treatments

Because flukes are naturally clear a visual confirmation is nearly impossible. Confirmation of flukes can be obtained via a freshwater dip. After 3-5 minutes the fluke will become opaque and dislodge from the fish. Although helpful, it is not a necessity, to identify the fluke’s family to aid in treatment. A microscope can confirm a species, however, Neobenedenia, can be seen with the naked eye.

1. Praziquantel or Prazipro – There have been several studies demonstrating various applications of Prazi. For practicality only a couple is listed. Prazi does not kill flukes. It induces uncontrollable spasms to where the fluke dislodges from the fish and continues to spasm. Studies have shown that after 10 hours the fluke dies. Prazi is very gentle on fish to the point it can be overdosed with no ill effects. The exception is wrasses. They are able to handle the 2.5 mg dosage but anything over that can be detrimental. It has also been reported that Prazi is safe to use in a reef aquarium with minimal casualties such as feathers and other worms. A word of caution: Prazi can act as an appetite suppressant. It also depletes the oxygen in the tank so be sure to fully aerate during treatment.
a. The most common method of dosing Prazi is dosing 2.5 mg for 5-7 days, then performing a water change, and finally redosing the full amount for another 5-7 days. A third and fourth dose may be necessary. Prazipro is reportedly (via personal communication with Hikari) “out of the water” 72 hours after the initial dose. However, once treatment is concluded it is recommended to do a large water change and add carbon to remove all traces of Prazi.
b. Another method is to do (2) 40 hour baths 48 hours apart in 5 mg/L Prazi.
NOTE: In 2013 research done, as reported in Aquaculture Volumes 404-405 Prazipro was shown to be 82% effective against Neobenedenia girallae.

2. Hyposalinity – Scientific research also showed hyposalinity at 15 ppt for 2 days eliminated juvenile and adult flukes. When maintained for 5 days, egg hatching was prevented.

3. Formalin dips – Water temp <70° 250 ppm for 30 minutes, water temp >70° or formalin sensitive fish 150 ppm for no more than 45 minutes. These dips can be repeated every 5-7 days. As always with formalin aerate for at least one hour prior to dip.

4. Freshwater dips – can be effective against skin flukes, however, it is ineffective against flukes in the gills.

Monitoring the fish for 30 days after treatment has concluded is important. Fish may continue to scratch after treatment due to their skin healing from the fluke’s hooks that were inserted into their skin. Confirmation of eradication can be confirmed by performing freshwater dips, skins scrapes and fin clipping. Obviously these should only be done by those with experience.

The lifecycle without a host can be completed within a few days. An adult can live up to 6 days without a host. After an egg hatches the oncomiridium must find a host within 36 hours or it will die. A fluke cannot attack an invertebrate or coral. There are no reports of flukes or eggs lying dormant as in Cryptocaryon. Equipment can be cleaned with hot water and bleach and thoroughly dried. As with all parasites and diseases avoid cross contamination with hands, equipment, water and food.

(prepared by Newsmyrna80)

Another good source of info on flukes can be found here: http://fisheries.tamu.edu/files/2013/09/Monogenean-Parasites-of-Fish.pdf

And here: https://edis.ifas.ufl.edu/fa033

Flukes on a fish:

ENcavzp.jpg
skinflukes1.jpg


Dead flukes in a freshwater dip:

943
944


An adult Neobenedenia sp. detached from its host:

neobenedenia.png
 
Last edited:

kartrsu

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If you are treating gill flukes, how would you know prazi was successful if you can’t really see them. Do you still FW dip and look for traces on black background?
 

Dierks

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If you are treating gill flukes, how would you know prazi was successful if you can’t really see them. Do you still FW dip and look for traces on black background?
The yawning, breathing heavy and/or scratching would stop. The only other way to verify this would be to take a gill sample.
 

Humblefish

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Anyone else run into gill flukes that persist with hyposalinity? I see everywhere rjat 1.015 or lower should kill them, but 17 days into hypo, the flukes seem to actually be worse. Dosed general cure to rid them (hopefully) but it would make me worried that I'm the only one to have flukes survive hypo
I question the efficacy of Hyposalinity sometimes. It just seems better at "controlling" Ich/Flukes than actually eliminating them.

@Dierks and I have talked about the effectiveness of Fenbendazole, and I'll ask him to chime in here; but that and formalin are probably the strongest treatments for prazi resistant gill flukes: Fenbendazole
 

Jposch

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I question the efficacy of Hyposalinity sometimes. It just seems better at "controlling" Ich/Flukes than actually eliminating them.

@Dierks and I have talked about the effectiveness of Fenbendazole, and I'll ask him to chime in here; but that and formalin are probably the strongest treatments for prazi resistant gill flukes: Fenbendazole
Yeah, he is actually less than an hour away from me, so ill be harassing him until he cuts me off. 🤣 I do think I should not relay on Chloroquine as much. Between the bans, and sensitivity issues. Idk. But, as I was telling him, the 40mg dosage is bade off of a study that was limited to 1hr. Exposure, only tested one life stage, and no other parameters were modified either. I wonder If say, a 10mg dose with hypo could be enough. Open treatment up for the sensitive fish. I just need to find some heavily invested fish to run trials on. So many questions that are unanswered at this point. I don't mind that flukes can survive CP, as makes me feel better about the effects it has on the fish themselves. I started using it before copper power came out. So I guess I'm biased as can be.
 

kartrsu

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I question the efficacy of Hyposalinity sometimes. It just seems better at "controlling" Ich/Flukes than actually eliminating them.

@Dierks and I have talked about the effectiveness of Fenbendazole, and I'll ask him to chime in here; but that and formalin are probably the strongest treatments for prazi resistant gill flukes: Fenbendazole
I am preparing to treat my tank with fenbendazole to kill hydroids. They are getting outta control and are affecting my corals. I’ve seen it as a successful last resort protocol that is pretty reef safe except for snails and some softies. The recommended dose is 1.5mg per 10G. Is that enough to kill gill flukes too? Prazi does not seem to be 100% effective for me.
 

Dierks

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I’ve seen it as a successful last resort protocol that is pretty reef safe except for snails and some softies
Be careful as @Jessican said that it did a number on her coral. I dont recall what ones.

Big Fan of fenbendazole... I do dose it quite often, and usually use it as a second treatment after one dosing of Prazi. I really think it might do a number on the eggs as well, but I have nothing to back that up with. I wish I had access to flukes and a lab!!
 

Humblefish

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I am preparing to treat my tank with fenbendazole to kill hydroids. They are getting outta control and are affecting my corals. I’ve seen it as a successful last resort protocol that is pretty reef safe except for snails and some softies. The recommended dose is 1.5mg per 10G. Is that enough to kill gill flukes too? Prazi does not seem to be 100% effective for me.
According to Noga, 25 mg/L (95 mg/gallon) is required for 12 hours in order to treat flukes.
 

Humblefish

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I think he is looking to kill off his Hydroids -- Those tiny feather duster looking things I believe.
Yes, but he was also asking if the 1.5mg per 10G dosage was good enough to kill gill flukes. I was just pointing out that it wouldn't even be close for doing that.
 

Jessican

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Be careful as @Jessican said that it did a number on her coral. I dont recall what ones.

Big Fan of fenbendazole... I do dose it quite often, and usually use it as a second treatment after one dosing of Prazi. I really think it might do a number on the eggs as well, but I have nothing to back that up with. I wish I had access to flukes and a lab!!
This site gives a good run down of what it will affect: Fenbendazole (Panacur) | Seahorse.com

Personally, I lost all leathers (except a cabbage leather), Kenya trees, blue sympodium, gorgonians, and a pipe organ that I recall.
 

Jessican

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Thank you so much for the reference. Did you lose any inverts besides snails?
Here’s my list, although I can’t say for sure that they were all due to the fenbendazole:

Invert losses: All trochus, margarita, and turbo snails, 1 tropical abalone, 2 cleaner shrimp, 1 pincushion urchin, and 1 maxima clam

Coral losses: Only softies/polyps (pipe organ coral, toadstool leather, finger leather, multiple purple gorgonians, several kenya trees, blue sympodium)

Invert survivors: All nerite, cerith, and bumblebee snails, all money cowries, 1 tropical abalone, fighting conch, electric flame scallop, various hermit/pitho/strawberry/pom pom crabs, rock flower/BTA/mini carpet anemones, 1 cleaner shrimp, 1 sexy shrimp 3 urchins (tuxedo, short spine, and Halloween), and 1 maxima clam. The BTAs actually continued to split like crazy while I was doing this – there were probably 12 in the tank when I started, and that number at least doubled.

Coral survivors: SPS frags (pocillapora, millepora, digitata, bonsai acro, various montis, psammacora, potato chip, elephant skin), large monti cap, variety of LPS (frogspawns, hammers, torches, cristata, acans, favias, pearl bubble, leptastrea, gonis/alveoporas, moseleya, fungia plate, turbinara, duncans, lobos, galaxea, blastos, candy cane, pectinia), one zoa colony (it actually went from 2 polyps to 5), and several mushrooms
 

kartrsu

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Here’s my list, although I can’t say for sure that they were all due to the fenbendazole:

Invert losses: All trochus, margarita, and turbo snails, 1 tropical abalone, 2 cleaner shrimp, 1 pincushion urchin, and 1 maxima clam

Coral losses: Only softies/polyps (pipe organ coral, toadstool leather, finger leather, multiple purple gorgonians, several kenya trees, blue sympodium)

Invert survivors: All nerite, cerith, and bumblebee snails, all money cowries, 1 tropical abalone, fighting conch, electric flame scallop, various hermit/pitho/strawberry/pom pom crabs, rock flower/BTA/mini carpet anemones, 1 cleaner shrimp, 1 sexy shrimp 3 urchins (tuxedo, short spine, and Halloween), and 1 maxima clam. The BTAs actually continued to split like crazy while I was doing this – there were probably 12 in the tank when I started, and that number at least doubled.

Coral survivors: SPS frags (pocillapora, millepora, digitata, bonsai acro, various montis, psammacora, potato chip, elephant skin), large monti cap, variety of LPS (frogspawns, hammers, torches, cristata, acans, favias, pearl bubble, leptastrea, gonis/alveoporas, moseleya, fungia plate, turbinara, duncans, lobos, galaxea, blastos, candy cane, pectinia), one zoa colony (it actually went from 2 polyps to 5), and several mushrooms
This is such a helpful post. Thank you thank you thank you. What were you treating in the tank and what concentration? Do I need to get DMSO for this to be effective?
 

Jessican

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This is such a helpful post. Thank you thank you thank you. What were you treating in the tank and what concentration? Do I need to get DMSO for this to be effective?
I actually didn’t mean to use fenbendazole - I had ordered prazi and was sent the wrong thing, and didn’t realize it until the second time I used it and wiped out the new softies that I’d gotten. :( I was just trying to treat flukes. The only time I intentionally used fenbendazole was as a 12 hour bath treatment, and DMSO definitely made a huge difference in getting it to dissolve.
 

kartrsu

Active member
I actually didn’t mean to use fenbendazole - I had ordered prazi and was sent the wrong thing, and didn’t realize it until the second time I used it and wiped out the new softies that I’d gotten. :( I was just trying to treat flukes. The only time I intentionally used fenbendazole was as a 12 hour bath treatment, and DMSO definitely made a huge difference in getting it to dissolve.
Man, can’t imagine your reaction upon finding out. Glad most of the inhabitants turned out okay after dosing though. Thanks for the help again!
 
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