Neon tetra disease?


Apr 16, 2011
Highlands of Scotland

Have suffered an almost total wipeout on one of my tanks over the past fortnight and I'm now suspecting neon tetra diease. Having never experienced this before and obviously wanting to attempt to keep the rest alive if possible, I'm wondering if you guys can help me?

The tank is a Lido 120 (so 120l) and has been running for almost 5 years. Temp is 24, though recently has been pushing to 27 due to the hot weather (ended up having to turn off the lights, but plenty of aeration). Ammonia and nitrite both 0, pH about 7.4, nitrates around 10ppm on average (never above 20ppm in this tank). Inhabitants were around a dozen black phantom tetras, bekfordi pencil fish and a female BN. The last fish I added to to this were 4 black phantoms around 14 months ago. I follow strict hygiene with my tanks, so no water from another tank has contaminated it (all my other tanks are fine, no issues). I haven't added any new plants for years and I don't use live food, just dry and frozen. I do 20% weekly water change and gravel wash. I never leave dead fish in the tank, and I do euthanise if I feel a fish is clearly beyond help.

I did have more pencil fish, who have gradually dwindled over the past couple of years, but other than one with dropsy, it doesn't seem to have been a particular disease. However, all of my black phantoms have eventually developed weird white/yellowy lumps around their tails and dorsal fin, went off their food, became anti-social, then were found dead. Up until recently, the lumps would be present for at least a few to several months in some cases with no other symptoms, then the eventual decline would happen over a few days. Because it took so long to happen, I wondered if it was just natural ageing, especially as it would generally only affect one fish at a time. However, I've gone from fine, to lumps, to death within days with 5 phantoms, all of whom have died within the past ten days (I've lost 3 in the past 48 hours). :(

Thankfully, my BN and the two pencil fish are fine. The last remaining black phantom looks OK this morning, but I'm monitoring her closely. Could this be neon tetra disease? I now have 3 miserable small fish who clearly need more company (the BN is fine), but I'm unwilling to risk moving them to another tank in case I spread the disease, or subject new fish to a potential death tank. I always thought neon tetra disease killed within a week, I didn't think fish could potentially have symptoms for months. I wondered if the increase in temperature could have accelerated the progress of the disease? Can anyone offer any advice as to what I should do? I feel so sorry for these poor fish right now!



Pleco Profiles Moderator - RIP FRIEND
Sep 9, 2010
Sorry for your loss and illness. The last outbreak I had was a long long tim ago and in my experiences this is not a nice disease. I would add an airstone for more oxygen to get into the system. I would do weekly water change of 30% and gravel vac only every month and not every week. I find if you gravel vac weekly it unsettles the system. Try feeding less and take it slow. I found medications for ME did not work. I just had to let it run its course. I would however wait till all symptoms are gone befoe even adding new fish, however these must also go through the Quarantine tank etc. Good luck and again sorry cheers jk :thumbup: