Honey Gourami with weird underskin issue

Hi all!
Maybe anyone here would have any advice or seen anything similar... We bought 3 honey gourami from a local aquatic store. When we were buying them, a guy in a store changed one of them since he noticed white patch on its side. Rest of them looked good in the store. When at home, we put them in a quarantine tank before adding them to our cherry barbs and corydoras tank. When I examined them in good light in the QT I noticed dark/brown dots (quite round but not perfectly round) under their skin (it is visible on one side of the fish and especially when it swims in front of light so I can see through it a bit.) 2 out of 3 have those. One of gouramis has two of those dots a bit under the start of its dorsal fin and a third dot on its spine height in 1/3 of a length of a body. Second gourami has the same dots under skin above and under spine area also around ⅓ of a body length, also visible from one side.

We searched internet for something similar but there is not much, the most similar case visually that we found is a single post on reddit with not much interest in it but from what the author of the post was saying - he decided to do a dissection and found something worm-like surrounded by brown/black goo.

Our gouramis seem to be okay with their behaviour and are eating and swimming properly. After reading this reddit post and asking for the advice from the aquatic store (they said they can change them for different ones if we want to and they said that they have never seen anything like that) we decided to keep them and treated them for parasites as there was a chance it could be caused by flukes. After 2-3 days of treatment (anti-fluke & wormer, Contents: Flubendazole) we started to notice a bit of the dark spots clearing itself. Now we could see like a transparent bubble with a bit of dark remainings on the sides on some of the spots under the skin - so we thought it’s helping and maybe the body started dissolving whatever it was. But after another few days it seems to not get any better. Also a few days into treatment one of the gouramis had almost an invisible string like tissue(?) (around 1.5-2 cm) coming out of its body (next to the beginning of its dorsal fin). We dabbed it with Methylene Blue and we haven't seen anything like that again on any of them.

And now we started thinking more on that - is the treatment not the right one?

We remembered there was a white patch on one of the gouramis in the store and now we thought - was it Columnaris? Especially after finding this string-like tissue coming out of the fish? And if it was there are few ways Columnaris can go - and we found out that there is something like Black Patch Necrosis that is quite rare. ’Black necrotic tissue is formed when healthy tissue dies and becomes dehydrated, typically as a result of local ischemia.’ So can it be any form of Columnaris getting to that stage?

We are monitoring the water parameters with API test kit and have them with a filter (media in it taken from a fully cycled filter from another tank) and an air pump. Added a little plant so they can feel a bit more secure.

Some of their poo is looking okay, then some of it is more stringy, long and uneven in colour and form.

Anyway, Does anyone have any other ideas? Is there any treatment that comes to your mind? Has anyone ever seen something like that on gourami or any other fish?

We are on the 2nd week of treatment with Flubendazole, also based in the UK so have limited access to some meds specifically with antibiotics.

And sorry for the length - I just thought it may be better to say too much than too little.
We really want to help those little buddies. Added pics, hope they are visible
Cheers!

@Colin_T should be able to help he is good with diseases if one would be present.

Rule one: If one fish in a tank looks even slightly off to you, don't buy from the tank. Wait, or buy elsewhere. Communicable diseases get around.

Right now, it's just caution that's called for. It could just be pigment on the skin. If it develops into a rectangular plaque-like sore, euthanize the fish. If it doesn't, you're okay and so are the fish. If it's a worm (unlikely) it would be a bird parasite using the fish to get to its home, and those are not trouble, and not common. I've seen them on wild local fish, but never on an aquarium fish.

You would need a biopsy or a dissection to be sure, but my concern is Mycobacter. It's an incurable untreatable bacterial infection sometimes called fish tuberculosis. The hobby has a terrible time with it, and industry connected people tend to talk like it doesn't exist. It's a disease with a scary name that spreads well on crowded fish farms, and afflicts a lot of fish who carry it, encyst it, and get on with what will be shorter lives because of it. Under stress, like shipping and selling, it can flare up, and is capable of jumping the species barrier and causing skin sores on humans. I've had it, which made me research the disease carefully during my 6 month antibiotic treatment. It's very rare to catch it, but if you have cuts, be cautious.

The lesions in the first shot fit the shape, but all the other photos look like pigment to me. Those are inbred, modified gouramis, and they do get marks they are not supposed to.

So monitor it. Use no meds, as there are none we can get for anything that would be. Keep the fish well, and see if they stay healthy.

Thank you @Stefan3289 for fast reply, hopefully @Colin_T wouldn't mind taking a look
Btw Pictures in the opening message are from the first day - before putting the treatment in as those were the only pictures I had. I will attach pictures with current state here - as the issue looks like it started clearing itself a bit. I tried different camera settings to show it more clearly. And between the first day to now it is not as dark as it used to be.

GaryE said:

Rule one: If one fish in a tank looks even slightly off to you, don't buy from the tank. Wait, or buy elsewhere. Communicable diseases get around.

Right now, it's just caution that's called for. It could just be pigment on the skin. If it develops into a rectangular plaque-like sore, euthanize the fish. If it doesn't, you're okay and so are the fish. If it's a worm (unlikely) it would be a bird parasite using the fish to get to its home, and those are not trouble, and not common. I've seen them on wild local fish, but never on an aquarium fish.

You would need a biopsy or a dissection to be sure, but my concern is Mycobacter. It's an incurable untreatable bacterial infection sometimes called fish tuberculosis. The hobby has a terrible time with it, and industry connected people tend to talk like it doesn't exist. It's a disease with a scary name that spreads well on crowded fish farms, and afflicts a lot of fish who carry it, encyst it, and get on with what will be shorter lives because of it. Under stress, like shipping and selling, it can flare up, and is capable of jumping the species barrier and causing skin sores on humans. I've had it, which made me research the disease carefully during my 6 month antibiotic treatment. It's very rare to catch it, but if you have cuts, be cautious.

The lesions in the first shot fit the shape, but all the other photos look like pigment to me. Those are inbred, modified gouramis, and they do get marks they are not supposed to.

So monitor it. Use no meds, as there are none we can get for anything that would be. Keep the fish well, and see if they stay healthy.

Click to expand...

Thank you for sharing your experience and I'm sorry to hear it affected you.
we understood the risk of taking them from the same tank as the one with a white patch however as we were putting them in QT we were willing to give them a chance.

I understand it's difficult to see from the pics, however these dark spots/patches on them definitely seem to be under the skin/scales and not on the surface, they are harder to see unless the light is shining through. So we are sure those are not the colouration on the skin.

Also it is interesting about the modified gourami, after reading your reply we tried to find something about it but failed - if you have any links/sources we could read about it, it would be much appreciated, thanks

If you wish to see some more pictures we added more (as a reply to Stefan3289) after they were treated with Flubendazole and it looks a bit emptier as there is a little bubble/empty space(?)

Cheers

I agree that this is likely to be pigmentation that was more visible when the fish were stressed after travelling. But the white mark on the store fish is of concern.
In addition to watch and wait, keep them quarantined for 4 weeks minimum. Restart the 4 weeks if they get new symptoms. Add some floating plants to make them more comfortable.
Finish the worming medication that you started. I de-worm all my quarantined fish as the medication is tolerated well and the likelihood of worms is high. People who have tried to treat worms in display tanks have to repeat the process as it takes a lot of time and effort to eradicate them once they are in the system.

The reason I raised what many consider an alarming possibility is that Myco is internal, and comes up from under the skin, as you described. Hopefully, it's not that.

The fish in your photos have an overall golden colour that is the result of selective breeding. Take a look online for Trichogasater chuna, or the older scientific name Colisa chuna, and you'll see what the original fish marketed as a honey gourami looks like.

Parasitic worm that ended up in the water with the fish and the worm larvae got lost in the fish's body and lives there now. It doesn't spread but sometimes the worms eat their way out and the fish either dies or heals up. Deworming medications like flubendazole might kill it but the dead worm will remain in the muscle tissue.

GaryE said:

The reason I raised what many consider an alarming possibility is that Myco is internal, and comes up from under the skin, as you described. Hopefully, it's not that.

The fish in your photos have an overall golden colour that is the result of selective breeding. Take a look online for Trichogasater chuna, or the older scientific name Colisa chuna, and you'll see what the original fish marketed as a honey gourami looks like.

Click to expand...

Thank you, looked them up, such a pity it's easier to get the modified ones these days.

Colin_T said:

Parasitic worm that ended up in the water with the fish and the worm larvae got lost in the fish's body and lives there now. It doesn't spread but sometimes the worms eat their way out and the fish either dies or heals up. Deworming medications like flubendazole might kill it but the dead worm will remain in the muscle tissue.

Click to expand...

Thanks so much for your insight. Quick question - I'm presuming it is okay to add them to a community tank after quarantine is up and no new issues come up?
Cheers

There is a possibility of gnathostomiasis (under the skin worms/larvae) in tropicals, but among tens of thousands of fish I dealt with in the fish importing business, I don't recall ever seeing a lesion caused by them. We always showed each other new to us parasites, because we were all very interested in them. It's a technical possibility, and may be a thing in Australia, where Colin worked, but...

I would keep the affected fish at least in QT til it resoloved itself one way or another. Watch the shape of the lesion and see if it becomes squared or rectangular. A fish with an active case of the extremely common Myco can take your whole tank out. All your fish would have it and have it under control, but if the sore opens the number of bacteria that can pour out can overwhelm the defences of the other fish. I would qt for at least a few months, and if the under the skin swelling didn't vanish, would euthanize.

Kirysek said:

Thanks so much for your insight. Quick question - I'm presuming it is okay to add them to a community tank after quarantine is up and no new issues come up?
Cheers

Click to expand...

Keep them quarantined for at least a month and they should be fine. If you want to err on the side of caution due to possible Fish TB (I doubt it is TB), then keep them quarantined for a few months. If it hasn't changed in that time then it isn't TB and isn't going to cause problems to other fish.

Take pictures of them each week and compared the spots, see if they change.