Gill ulcer - TB?

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Fish Aficionado
Jun 2, 2019
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4 or 5 years ago I bought praecox melatonia and a lot died in quarantine, the main symptom was opening and closing the mouth. 3 batches and they nearly all seemed to succumb.

This last one has a yellow/ orange growth in the gill and I wonder if anyone can confirm if it looks like TB. I run a closed system anyway but would like to know for sure.


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Can't tell what that is from the angle. If it sticks out from the gill cover, post more pictures showing it from different angles.

Gill tumours are normally pink or flesh coloured and stick out from underneath the gill cover. If the orange dot is on the outside of the gill cover, it's unlikely to be a tumour caused by Fish TB.

Fish TB normally kills rainbowfish within 1-2 years (3 yrs max if they are kept in cool water for half the year). If you have had the fish for more than 3 yrs, it's unlikely to be TB unless you added new fish during that time.


When rainbowfish are newly imported, add salt to the tank straight away. It helps stop fungal and bacterial infections in their mouths/ throats that kill them.
Use 2 heaped tablespoons of rock salt per 20 litres (5 gallons) of water. Keep the salt in there for 2-4 weeks.
Thank you. I'll try for more pics tomorrow. I'm sure she is older than 3.
You advised me about the salt when I got them and I have also followed your advice by feeding plant matter. But I haven't been able to keep them in temperate heat in winter as they are/were in a community tank.
Most tropical community fishes can live in water with a temperature around 18-22C.
I don't know anything about it really, no help, just wanted to say I'm sorry you lost all those fish, and now have that worry with this one too. :( :rip: Fish TB is a really scary one, and I remember Colin and @Wills discussing how often rainbowfish are infected with TB now, so I'd be really worried too.

When you say you run a closed system, what does that mean? Just curious to learn more, sorry I can't help, but sending cyber hugs and support anyway!
When you say you run a closed system, what does that mean?
Just that no fish have been added nor switched out of the rainbow tank since the problem started and trying reduce cross transfer between tanks via equipment/ plants.

That first batch clearly had something but some fish looked good after an extended quarantine (another month after the last death with no symptoms for that month) so they went in the main tank and I got another shoal to add to the couple that were left, also quarantined successfully. The main tank had some symptoms and deaths but after a clear period I got another shoal to add to the remaining few and again lost a load so gave up. For the last couple of years I just had one pair but I had to euthanise the big beautiful male not long ago which was such a shame. Now the little lone female has the ulcer.
This may be late, and may not be news but be careful. I’ve heard that TB in fish can spread to us.
The following links have more info on Fish TB in people.

It does not look like a fish tb lesion. (If you looked in the first 30 seconds this was up, I had typed too fast and left 'not' out).

I have a certain expertise with fish tb in humans, since I've had it, and it's cured.

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