What's this worm?

[Viktor Jarikov]

Hi All,

Had to dissect a ~15" peacock bass today. Turned out it had some kind of internal worms:

-- all about the same size, ~2"-3" long, 1/32"-1/16" diameter, see photos;
-- reside coiled-up tightly, ~3/16" coil diameter, deep within the fish flesh, in pure muscle,
-- everywhere in the flesh, looks like a worm per 1-2 cubic inches,
-- does not appear to be in the intestine although I have not looked too carefully there; the intestine cavity was ~2/3 hollow;
-- the fish looked sickly but not deathly sick, just rough, eyes appeared to be ~2x too big for it, tummy sucked in a bit, fins are a bit misshapen

Does anyone know what this worm is and what treatment would kill it best? Praziquantel? Fenbendazole?

Thanks.

Viktor

[bekateen]

-- reside coiled-up tightly, ~3/16" coil diameter, deep within the fish flesh, in pure muscle,

There are lots of worms that encyst in flesh, but this reminds me of trichinosis, which is caused by a type of roundworm. (EDIT: I'm not saying it IS trichinosis, I'm just saying that the parasite, its shape, and its behavior REMIND me of trichinosis) Also, your photos show worms that are consistent with being nematodes (roundworms), as far as I can tell (although again, lots of worms might look similar).

I'm not well experienced with fish medications, but you might be able to treat it with any other medication that works on nematodes. Alas, I don't know what that would be.

Out of curiosity, I looked up trichinosis in humans to see how it's treated. At the Mayo Clinic website, they say this:

Anti-parasitic medication. Anti-parasitic (anti-helminthic) medication is the first line of treatment against trichinosis. If the trichinella parasite is discovered early, in the intestinal phase, albendazole (Albenza) or mebendazole can be effective in eliminating the intestinal worms and larvae. You may have mild gastrointestinal side effects during the course of treatment.

If the disease is discovered after the larvae bury themselves in tissues, the benefit of anti-parasitic medications is less certain. (emphasis added by me). Your doctor might prescribe one if you have central nervous system, cardiac or respiratory problems as a result of the invasion

Regards, Eric (I would have signed off with my standard "Cheers," but somehow talking about parasites doesn't seem like anything to be cheery about. )

[Viktor Jarikov]

Many thanks, Eric.

Looks to me a Eustrongylides species. This is one of the most useful treatises on it I found so far: https://edis.ifas.ufl.edu/fa091 Pretty much no cure.

[bekateen]

At least at a preliminary level, I would agree with you; otherwise, I don't know more about these parasites to be more helpful. From your photos and description I could tell it was a nematode, I just couldn't tell what KIND of nematode it was.

And like the Mayo Clinic says about humans, in the fish there is really no good treatment other than surgical removal. I suppose if you had only one or two worms inside a fish and your surgical skills are up to the challenge, you might give it a try for some fish you really want to save desperately. But otherwise, as the web source you cited mentions, culling is really the only viable treatment.

Sorry Victor.

Eric

[Silurus]

I'm inclined to think the nematode is Philometroides rather than Eustrongylides, but this is a rather moot academic point.

[mickey3]

Is there any risk of fish to fish transmission with Philometroides?

[bekateen]

Directly? I would not expect so. The Philometroides which I looked up use copepods as intermediate hosts in their life cycle. I don't believe there is any ability to transmit from fish to fish directly.

[Viktor Jarikov]

Thanks much, guys. I cannot find any popular write-up that would describe Philometroides and issues for a layman, in a similar manner to the one linked above.

Silurus, are you saying "moot" because they have the same life-cycle, biology, and treatment (if any)?

Sister thread on MFK http://www.monsterfishkeepers.com/forum ... rm.652973/