Jump to content

Mysterious disease in community tank? Please help!


Recommended Posts

I need help identifying/treating a possible disease in my tropical community tank. 
I came into the Aquarium Co-op about a month ago for advice after a couple of fish mysteriously died a few weeks apart and another one was showing white spots. Unsure if these issues were related, I decided to treat the entire tank. A nice young man working at the co-op looked at a photo of the fish with white spots, said it doesn't look like ich, and advised I try adding aquarium salt and Maracyn first, followed by Ich-X and Paracleanse if that wasn't effective. 
After finishing the treatments with salt, Maracyn, and Ich-X (and removing almost all of the salt through a series of water changes), one of my cory catfish died unexpectedly this past weekend, after which I began treating with Paracleanse. Then today I noticed a black neon tetra apparently on the brink of death, losing most of its color and struggling to swim. That fish is currently in quarantine and I don't expect it to live much longer. 
My question is: Should I try treating the tank with something else, since the salt/Maracyn/Ich-X/Paracleanse treatments haven't cleared up the white spots on the black neon tetra and two other fish have died since starting the treatments? And should I give my fish a break before trying something else?
No other fish have visible symptoms at this time. I suppose it's also possible that these fish could be dying of old age, as I've had them all for more than 2 years, but it seems odd that several fish have randomly died within two months of each other when there had been no other deaths in this tank since it was set up back in early 2021. The white spots on the black neon tetra definitely seem suspicious, although they appear to have gotten just slightly smaller over time. 
The tank is 29 gallons, has several live plants, and currently has the following stock:
– 6 Florida Flag Fish
– 5 Lemon Tetra
– 4 X-Ray Tetra
– 4 Black Neon Tetra
– 5 Albino Cory Catfish
– 1 Bristlenose Pleco
– 8 Nerite Snails
Ammonia: 0
Nitrite: 0
Nitrate: <5 ppm
PH: 6.8-7.0
Temperature: 77 F
Filtration: AquaClear 50 HOB filter with carbon filter and Purigen, plus a 20-gallon sponge filter 
In case it's helpful, here's a log of recent events, with deaths and symptoms in bold: 
(Note: This list doesn't include all water changes. I diligently do a 30% water change every weekend in addition to what's listed here.)
  • Feb 4 - RIP Paradise Fish
  • Feb (?) - Euthanized an X-ray tetra with an apparent spinal deformity that was struggling to swim and eat. This was a long-term problem that got only recently got worse. Not sure if this fish had a disease or if it simply had a "birth defect," but I suspect the latter.
  • Feb (?) - Quarantined a bloated Black Neon Tetra, treated with Tetra Lifeguard + aquarium salt for about a week and returned to tank in apparent good health 
  • Feb 20 - Added 6 Florida Flagfish
  • March 13 - RIP Silvertip Tetra
  • March 14 - Noticed white spots on a different Black Neon Tetra (irregularly sized, raised lumps that do not look like ich)
  • March 15 - Added Maracyn and aquarium salt (2 Tbsp), removed chemical filtration
  • March 16 - Maracyn dose #2 + more aquarium salt (4 Tbsp, so now 6 Tbsp total in tank)
  • March 17 - Maracyn dose #3
  • March 18 - Maracyn dose #4
  • March 19 - Maracyn dose #5
  • March 20 - 30% water change and replaced chemical filtration (carbon filter + Purigen)
  • March 22 - Began Ich-X treatment (after another 30% water change and removing chemical filtration)
  • March 23 - Ich-X dose #2 (after 30% water change)
  • March 24 - Ich-X dose #3 (after 30% water change)
  • March 25 - Ich-X dose #4 (after 30% water change)
  • March 26 - 30% water change, replaced chemical filtration
  • April 9 - RIP Cory Catfish
  • April 9 - Added Paracleanse (first dose) after 30% water change and removing chemical filtration
  • April 11 - Paracleanse dose #2
  • April 12 - RIP Black Neon Tetra, probably (not the same one with the white spots, that fish is alive and seems to be doing well but still has the same white spots. Unsure if it's the same fish we previously treated for bloat)
  • April 13 - Planning to do another 30% water change and replace chemical filtration as the Paracleanse treatment is complete
  • Like 1
Link to comment
Share on other sites

Wow. There’s a lot to unpack here but it sounds like you’ve tried all the potential treatments and changed a lot of water. 
The problem might be that you tried all the treatments and changed a lot of water. 

I guess when I mean is, it looks like there hasn’t been much consistency to the water parameters and biological filtration over the last 4-5 weeks. The cory and the black neon may have just had a hard time handing all the change.

The goal going forward should be consistency for the near future. Let the tank go. Let’s reestablish stable water parameters and build back up good biological filtration.

We have a tendency to tinker when we look for answers but sometimes our over reaction breeds more problems. We’ve all been there, believe me. 


Link to comment
Share on other sites

Thanks for the reply @ScottieB! I was kind of thinking the same thing. My concern has been that the white spots on the one black neon tetra could spread to other fish, and/or that some invisible pathogen is lurking in the tank just waiting for the opportunity to infect a stressed fish. I have never quarantined any newly purchased fish in the past, so it's possible I brought home something nefarious from my LFS at some point over the last two years and that it's just been dormant in the tank because my fish were all healthy up until recently. 

So, I used the "med trio" recommended by the Aquarium Co-op in an attempt to kill off any potential pathogens in the tank and start over with a clean slate. At the bottom of that page it says that for weak fish (although I don't think my fish were weak), instead of dosing all three meds together for one week, you can use them one at a time over the course of three weeks. I thought I'd be doing the fish a favor by spreading out the treatments, but I wonder if that just prolonged their discomfort and possibly even caused the two most recent deaths due to inconsistent water quality like you said. 

I'm thinking that the best course of action will be to just quarantine that one fish with the persistent and mysterious white spots, maybe try some other treatments exclusively in the quarantine tank, and hope that there's nothing malicious left in the main tank while I leave it alone for now. It's frustrating that after all of this fussing over medications, that darn black neon tetra STILL has the same white spots, and he doesn't seem bothered by it one bit! 😅

Link to comment
Share on other sites

@Colu Epistylis could be it! I hadn't heard of that one before. However this fish has had these spots for about a month now, so "commonly kills rapidly" doesn't really apply. The first pic here is from today, the second pic is from March 15. The spots on its gills have gotten much smaller, but there's more white on his dorsal fin now. He seems fine otherwise, still eating and shoaling with his friends as usual. 

April 12 - black neon still has white spots.jpg

March 15 - black neon with white spots.jpg

Link to comment
Share on other sites

If it's been a month with these spots it's more than likely not epistylis did you quarantine the flag fish before adding them to the main tank if no they could have bought in parasites that would explain the odd random deaths weeks apart I would Keep treating with paracleanse every two weeks for a total of three full courses of treatment I would quarantine the black neon tetra with the spots and treat with aquarium salt 1 table spoon for 1 gallon for 7days @Hanneke

Edited by Colu
Link to comment
Share on other sites

@Colu I did not quarantine the flag fish before adding. In fact, I've actually never quarantined any of the fish I've added to that tank (I know, bad fishkeeper!) which is why I suspect there could be some parasite or other disease-causing agent lurking in there. Most of my fish (including the flag fish) came from the Aquarium Co-op, which I trust to keep their fish healthy and disease-free, but a few came from another LFS that I don't trust as much. In hindsight probably should have just quarantined every new fish just to be safe. I will do that from now on. 

I'll try doing a couple more rounds of paracleanse like you said and hopefully the salty quarantine will help clear up the white spots on the black neon. Thanks so much for the advice!

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...