Pristella Tetra Mystery Disease

[Ginger]

First post here and it’s gonna be a long one because I want to give as much info as possible. 

 

I've been having a strange issue with my pristella tetras in my planted community tank. I first got them in mid December of 2020 and I want to say it was early February when I first noticed some small dark patches on one of them; It didn’t look like any diseases I’m familiar with and it was only one fish, so I just assumed it was some natural variation in color or scars I hadn't noticed before, but after a week or so the patches were bigger and it started swimming strangely so I moved it to my 10 gallon quarantine tank where it died the next day. It wasn’t until April 14th that I noticed another pristella tetra with similar patches, this time with a growth on it’s mouth and a small chunk of its tail missing. I immediately scooped the fish out and stuck it in a little 1 gallon quarantine tank. The main tank had already been treated with ICH-X as a precaution after I moved in a new neon (for just a few minutes) that had been in quarantine without noticing it’s ich, so that medication doesn’t seem to have an effect on whatever this is. I did start treating the pristella with KanaPlex in it’s quarantine tank, but that had no effect either. I never did see it eat after removing it, and it eventually started to swim very weakly/float around and died on April 28th. 

 

The same day that the second fish died, I managed to catch and quarantine a third pristella tetra that I noticed has the same dark patches (noticed maybe 5 days prior, but it was exceptionally hard to catch compared to the others), so far this one is alive but not eating and occasionally swims kinda weakly. I haven’t treated with anything since the meds I have on hand don’t seem to do anything, and I can’t for the life of me figure out what the issue is. The black patches start out just looking like pigmentation, but after a while they seem to turn into raised bumps. My many google searches show nothing that looks the same except for occasional forum posts much like this one where people are confused about dark patches on their fish and nobody is able to give a concrete diagnosis; seems like it’s only tetras but that could just be a product of my search terms. It just seems really strange to me that it’s happening to so few fish, only the pristella tetras so far, and so long after getting them.

 

The aquarium is a heavily planted low tech 55 gallon kept at 75F, weekly water changes of 50-70%, weekly doses of Easy Green and SeaChem Flourish Potassium. Ammonia and nitrites always test at or near enough to 0 ppm that I can’t tell the difference, nitrates hover between 10-20 ppm depending on how long since the last water change, PH is 7.5. Tank stock is 4 pristella tetras (originally 7), 6 neon tetras (more in the quarantine tank until I figure this out), 7 siamese algae eaters, 3 clown plecos, 1 otocinclus, a few dozen endler/guppy hybrids, and a bunch of cherry shrimp; everything else seems perfectly healthy including the remaining pristellas. I feed New Life Spectrum flake food, Hikari micro pellets, Fluval Bug Bites pleco formula, Hikari algae wafers, and Ocean Nutrition instant baby brine, no live foods ever. No fish have been added to the main tank since December other than the one neon for a few minutes and all issues that it and it's quarantine tankmates had have since cleared up. I have added new plants multiple times since first getting the fish so maybe something hitched a ride.

 

Other examples of people with similar looking disease problems, the third link has multiple people reporting similar symptoms:

http://www.wetwebmedia.com/PristellaF.htm

 

http://www.wetwebmedia.com/FWSubWebIndex/BlackNeonTetF.htm

 

https://www.aquariacentral.com/forums/threads/anyone-able-to-identify-black-spots.133788/

 

I don't have pictures of the first fish, so I can't compare to the other 2 and I guess it is possible that what it had was something completely different, which might explain the gap in time between them, but if memory serves me correctly it looked pretty much the same (with the base of the tail being the most prominent dark area) and in the third link above people mention months between infections.

 

It might be worth noting that I had a skinny female guppy die the other day, but I would just assume that was from old age, I can't keep track of all their ages, but there's been a population in there for years so that happens every once in a while and it wouldn't be unusual for them to waste away a bit before finally dying (it had no other symptoms and all other fish seem fine). 

 

Any help steering me in the right direction would be appreciated.

[Colu]

Black patches can be caused by an injury healing or ammonia burn or  necrosis of the skin caused by a bacterial infection am not sure 100% whats going on here

Edited May 4, 2021 by Colu

[Ginger]

Yeah, I've wondered if the black spots are just some kind of response to tissue damage, but I have no idea what could be causing it. There's no aggressive behavior in the tank that I can see and no real way they could easily injure themselves, so I figured it has to be some sort of disease (especially since it continues to get worse after isolation). I would think if it were a bacteria it would be a little more rampant but I really have no idea. For all I know everything is already infected with whatever this is and just isn't showing symptoms yet. 

[Colu]

You can get black spot disease that is usually not fatal recommend   treatment is praziquantel which is the active ingredient in paracleanse and general cure

[Ginger]

It could be black spot, but combined with the growth on the mouth and the fact that they're dying made me think otherwise. Black spot has a life cycle that requires contact with fish eating birds at some point and I'm not sure if pristella tetras are usually bred in outdoor ponds or not (from what I've read they're not usually wild caught). Not sure if black spot can be dormant for this long either. Almost seems like there's some kind of unknown disease out there affecting tetras based on the forum posts I've read; multiple people reporting black splotches showing up months apart and killing fish.

[Colu]

35 minutes ago, Ginger said:

It could be black spot, but combined with the growth on the mouth and the fact that they're dying made me think otherwise. Black spot has a life cycle that requires contact with fish eating birds at some point and I'm not sure if pristella tetras are usually bred in outdoor ponds or not (from what I've read they're not usually wild caught). Not sure if black spot can be dormant for this long either. Almost seems like there's some kind of unknown disease out there affecting tetras based on the forum posts I've read; multiple people reporting black splotches showing up months apart and killing fish.

That the only other illnesses I could think of that get the black patches your fish have

[Ginger]

Alright, I ordered some praziquantel (PraziPro), gonna give that a shot and see what happens.

[Ginger]

Well, surprising update. I was just looking at the isolated fish (fish #3) and noticed that it now has a very large chunk of it's tail missing and has larger growths on its sides. For some perspective on how fast this is changing, the 4th and 6th pictures on the original post were taken this morning at 1am and 8am respectively and its tail looked completely intact. I did notice the tail before I started the water change, so it's not an injury from netting it out or anything. It started floating on its side again after the water change so I got another close up photo. Hard to see on the pictures, but some of the dark patches look like they are deep in the muscles and not just on the surface, which sounds right for black spot, but everything else seems unrelated (maybe secondary infections of some kind?). 

[Colu]

1 minute ago, Ginger said:

Well, surprising update. I was just looking at the isolated fish (fish #3) and noticed that it now has a very large chunk of it's tail missing and has larger growths on its sides. For some perspective on how fast this is changing, the 4th and 6th pictures on the original post were taken this morning at 1am and 8am respectively and its tail looked completely intact. I did notice the tail before I started the water change, so it's not an injury from netting it out or anything. It started floating on its side again after the water change so I got another close up photo. Hard to see on the pictures, but some of the dark patches look like they are deep in the muscles and not just on the surface, which sounds right for black spot, but everything else seems unrelated (maybe secondary infections of some kind?). 

7 hours ago, Ginger said:

It could be black spot, but combined with the growth on the mouth and the fact that they're dying made me think otherwise. Black spot has a life cycle that requires contact with fish eating birds at some point and I'm not sure if pristella tetras are usually bred in outdoor ponds or not (from what I've read they're not usually wild caught). Not sure if black spot can be dormant for this long either. Almost seems like there's some kind of unknown disease out there affecting tetras based on the forum posts I've read; multiple people reporting black splotches showing up months apart and killing fish.

Maybe black spot with a secondary bacteria infection its difficult to for sure

[Ginger]

In the meantime, I've added some KanaPlex to the water, but based on my experience with the previous fish I doubt it'll do much. 

[laritheloud]

This is wild. If the Kanaplex isn't knocking it out, maybe it's viral? I have no idea. I'm sorry this is happening, it's so frustrating and sad. I hope you can stop the spread soon.