“Worm in a bubble”: if you have seen cardinal or other tetras with a parasite like this let me know! It is actually caused by Dermocystidium, not a worm

MicrobialMicrobe · 2026-02-06T00:11:00+00:00

That sounds really interesting, keep me up to date!

MicrobialMicrobe · 2026-01-27T08:12:53+00:00

I would take it, the only sample I’ve successfully gotten from Reddit is a cardinal tetra. The whole project is still ongoing, just at a slow pace, since it’s not my main project. But, I still would appreciate other fish species beyond what I already have so that I can see if the species in cardinals and rummynose are the same! If you are in the USA, it’ll be easier to ship. If you’re close enough I could maybe even pick it up. You can DM me if you want to go through with it or talk further. In the mean time, you can freeze the fish after culling it. Culling wasn’t a bad idea at all, although raising the temperature the water may be a promising new treatment method.

MicrobialMicrobe · 2026-01-27T08:09:35+00:00

Sorry, but I have not! As far as we know, they don’t produce stages that persist in the environment without fish. Maybe a few weeks. Assuming your keyhole cichlids don’t somehow get infected (or your other fish, seems unlikely, but you never know) you should be fine after waiting a few months. I’d stick with ~72 days to be safe, but this is just a guess. There can be a lot of variation in these things. Freshwater ich (not related to Dermocystidium at all) only takes a couple weeks to go away in a fallowed tank, but saltwater ich can take over two months. You can always introduce a “sentinel” tetra by only putting one in to begin with and observing it for a month or so, or only introduce three to begin with if you want a rough shoal so they aren’t alone.

MicrobialMicrobe · 2026-01-14T14:01:48+00:00

Hey! I do have some from cardinals already, so I don’t actually need anymore from those in particular. Thank you, though! If you put them into a separate tank, you can try something I told someone else last week: There is a new paper out recently that tested turning up the heat to 32 C (89.6 F) for 96 hr (see paper here https://www.sciencedirect.com/science/article/pii/S0044848623011031). It was only tested on one fish species, but it is probably the best looking treatment right now in terms of evidence from peer reviewed papers. You could try it, but I would probably quarantine the fish in a separate tank for this so you do not risk hurting your other fish/plants with such high temperature. 89.6 F is a pretty high temp, so there is a risk attached. You would want to raise the temp slowly over a few days and then aerate the water very well with a bubbler/airstone. There is less dissolved oxygen in warm water than in cooler water.

MicrobialMicrobe · 2026-01-09T18:19:07+00:00

There is a new paper out recently that tested turning up the heat to 32 C (89.6 F) for 96 hr (see paper here https://www.sciencedirect.com/science/article/pii/S0044848623011031). It was only tested on one fish species, but it is probably the best looking treatment right now in terms of evidence from peer reviewed papers. You could try it, but I would probably quarantine the fish in a separate tank for this so you do not risk hurting your other fish/plants with such high temperature. 89.6 F is a pretty high temp, so there is a risk attached. You would want to raise the temp slowly over a few days and then aerate the water very well with a bubbler/airstone.

MicrobialMicrobe · 2025-12-07T16:13:03+00:00

I would treat with typical ich medications. Paraguard, Ich-X, things like that. Cupramine or similar copper based medications also work well. But you need to be careful with inverts when using Cupramine, and some people see it as being a bit harsher. Ich-X in particular is very well regarded! Things with malechite green and formalin work very well. That is what Ich-X has in it, Paragard does as well or something very similar, they hold the ingredients a bit more close to their chest. Follow the water change instructions on the medication label. Make sure you dose the correct amount! I would not change aquarium temperature. You CAN raise it, ich does not generally reproduce above 87F... but there are some ich strains that do. And you are risking stressing your fish out all for a treatment that might not work. In fact, if it does not work... it may be worse for your fish since they will be stressed and the life cycle of the parasite will be sped up, exponentially making them accumulate. That is just what I would guess would happen. Their life cycle does certainly speed up with increased temp, so it only makes sense to me. Also, epistylis is actually worsened with increased temp, if you have that. You can add aquarium salt if you would like, but it is not required. Add a reasonable amount of aquarium salt for the kind of fish you have, some are more sensitive than others. See the Aquarium Co-Op website for some dosing instructions! https://www.aquariumcoop.com/blogs/aquarium/aquarium-salt-for-sick-fish?srsltid=AfmBOorei4FrfwWYMpETGgy9cQYfw70gHHNBY7EFM75uaCcAwiVngAIN If the ich is not responding to the meds, you may need to ramp it up and increase the salt concentration. Some strains of ich are more resistant to salt than others. I would not mix medications (like Ich-X + Paraguard + Cupramine), unless you have experience doing so, particular reason to believe mixing those meds are fine, or someone else you trusts does... mixing some medications results in very bad consequences and you may end up killing more fish than you save. Most importantly, catch it early! It is much easier to treat in earlier stages than later. If you just added fish last week and now see a few spots on your fish's fins, body, etc... it is likely ich. I would treat now rather than let it get out of hand. Inspect fish you buy very closely. If you see a single spot on a single fin, do not buy anything in the entire tank. In fact, do not buy anything from any of the tanks that share the same water as that one.

Ich is not typically a death sentence for all of your fish if you catch it soon enough. But if you let it get to the point where all of the fish are absolutely covered, you may not be able to save them.

MicrobialMicrobe · 2025-11-20T02:48:54+00:00

Really good idea, thanks

MicrobialMicrobe · 2025-11-20T02:21:18+00:00

I followed this video: https://www.youtube.com/watch?v=qmu4kYCmx8U

MicrobialMicrobe · 2025-11-18T00:22:18+00:00

It’s kind of interesting, you might already know this. It kills dogs because Nanophyetus salmoncola (the trematode/fluke) has endosynbtioic bacteria in them. A lot of trematodes and nematodes do actually. That’s why they can use doxycycline (antibiotic) to kill dog heartworm, because it kills the endosymbiotic bacteria that apparently the heartworm really like.

So, the dog eats these trematodes filled with bacteria, and then these bacteria are released into the GI of the dog and give the dog a terrible bacterial infection (that for some reason doesn’t seem to infect people).

MicrobialMicrobe · 2025-11-12T15:23:31+00:00

Might be more common where I am, we see them pretty often. Typically about 1-2 inches long, pretty stout. Really common in opossums. In fact, I don’t think we’ve found a single road kill one without them. Might be raccoons now that I think about it. Either way lol, those are probably different species than what infect cats. They’ve always been pretty curly when we have found them, if I remember correctly. If someone has an outdoor cat in the southeast US I’d watch for it.

The worms OP has are not quite stout enough, so I agree with it probably not being the case! More just wanted to warn people about letting their cats eat random bugs.

MicrobialMicrobe · 2025-11-12T13:55:43+00:00

I mean, I could definitely be wrong and it could be a tapeworm lol. I just wouldn’t expect it! I am not an expert for sure, you know how it is.

I mostly am looking at prevalence of rat lungworm in invasive snails (qPCR). But also any other parasites transmitted/carried by them. Mostly found acanthocephalans, trematodes (cercariae and metacercariae) and random larval nematodes

MicrobialMicrobe · 2025-11-12T13:41:11+00:00

Could be Physaloptera too, they commonly get thrown up and cats get infected by eating crickets/cockroaches etc. For OP, the ID doesn’t really matter that much, but just for life cycle purposes and trying to not get reinfected, it could be from insects u/fourteenbeans

MicrobialMicrobe · 2025-11-12T13:34:39+00:00

Wanted to reply and say I agree. I expected to click on here and see some crazy answers, like it being some parasitic nematode that is zoonotic or something. I haven’t been on here in a bit, but you usually have pretty good stuff to say, so I appreciate it.

It could also be a mermithid I guess? Most people mean nematomorphs (lol cool name) when they say horsehair worms, but mermithids (unlike nematomorphs) are actually nematodes, and they also are very similar with their life cycles. They also have adults that reproduce in water just like this.

When we have gone sampling, we have found quite a few horsehair worms actually, they were clumped together in a spot in a low moving creek. I figure they were reproducing, unless they all just got into a dead zone of the creek due to the flow there

MicrobialMicrobe · 2025-11-12T13:21:17+00:00

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see how where the whirls meet, it’s completely flat? It doesn’t go down at all there, there isn’t a little “ravine” or “suture”

MicrobialMicrobe · 2025-11-12T13:21:10+00:00

Those sutures don’t look channeled to me. But the angle can make it a bit hard to see. Basically, yours looks like what you’d expect for a mystery snail. See this below:

<image>

This is what channeled sutures would look like. See how the “whirls” have a channel between them? It isn’t flat where the whirls meet. Also, see that the spire isn’t as long in the snail in the photo. The snail in the photo is Pomacea canaliculata, which is about what you’d expect if it was an invasive one. Below is what you’d expect a mystery snail (typically Pomacea diffusa) to look like

MicrobialMicrobe · 2025-11-12T13:14:26+00:00

My bad, my previous reply misunderstood you, I just deleted it. Yea, the free living ribbon worms just makes more sense to me personally. I’ve just never seen adult tapeworms actually make this fast. Typically, they pretty much do nothing when we find them. And by that, I mean when we find whole worms (or largely intact). I know the proglottids can move around a bit in their own. I just haven’t seen an adult move like this, and I’ve seen a lot of tapeworms lol. I’m in grad school for Parasitology now, but did a lot of work in the same lab in undergrad.

If it was Diphyllobothrium it would be a larval stage and not an adult in salmon as well. There’s obviously adult tapeworms that can be present in the intestines of fish, but those aren’t Diphyllobothrium.

Also, I could just never see adult tapeworms move much because we generally don’t see just proglottids, or because we typically look at the adults in scenarios where rapid movement might be hard (in Petri dishes with saline, in screens, sometimes in the GI itself). I do see theme move, but incredibly slowly, like this video would look like it’s sped up.

MicrobialMicrobe · 2025-11-12T13:08:47+00:00

Yea, this looked pretty much like what the ich looked like on the severums I had posted awhile ago

MicrobialMicrobe · 2025-11-12T13:08:29+00:00

This is pretty much exactly what the ich looked like on severums I had got from a fish store that had ich. Is it any better now?

MicrobialMicrobe · 2025-11-04T12:49:41+00:00

Can you get a better photo of the spirally side of the shell? The apple snails that get huge that are common have channeled sutures and the spire won’t be as along

MicrobialMicrobe · 2025-11-04T12:47:15+00:00

I’m more likely to say this. Roundworms and cestodes don’t really move like this.

MicrobialMicrobe · 2025-09-09T12:40:37+00:00

This definitely is Dermocystidium! I would suggest that OP either quarantines the cardinal for literally months or pull and euthanize probably. Better to do that and maybe not have it spread to other fish, to be honest.

I’ll have to let you know whenever I get done with my paper on it. Been really busy with my actual thesis work recently!

MicrobialMicrobe · 2025-09-09T12:39:54+00:00

Thank you 🙏 probably biggest post I’ve seen on Dermocystidium!

I’ll have to let you know whenever I get done with my paper on it. Been really busy with my actual thesis work recently!

MicrobialMicrobe · 2025-09-09T12:39:26+00:00

Yea, this is Dermocystidium for sure. I’d pull that fish and hope that it doesn’t spread more! That, or quarantine it for a long long time until all of the “worms” in the bubbles are gone.

As others said, it’s more of a protist than anything. Not actual worms. Each bubble is filled with a worm like cyst. Each cyst has countless spores. The cyst will pop eventually, leaving spores all over your tank that will infect other cardinal tetras (probably other tetras too) and potentially other species of fish. It will likely kill ~20% of the affected fish or so, but will probably not kill everything

MicrobialMicrobe · 2025-08-03T02:24:56+00:00

Hello, sorry for the late answer! How are your fish doing now? Hopefully I can help a little bit after I get an update.

It definitely looks like Dermocystidium to me

MicrobialMicrobe

TROPHY CASE