White Growth in Jack Dempsey Mouth

[Deadeye]

Have you tested your water?

Yes

If yes, what is your ammonia?

0

If yes, what is your nitrite?

0

If yes, what is your nitrate?

<5

If I did not test my water...

...I recognize that I will likely be asked to do a test, and that water tests are critical for solving freshwater health problems.

Do you do water changes?

Yes

What percentage of water do you change?

81-90%

How frequently do you change your water?

Every two weeks

If I do not change my water...

...I recognize that I will likely be recommended to do a water change, and water changes are critical for preventing future freshwater health problems.

Brief history:
My Jack Dempsey had been refusing food for a bit, which I assumed had to do with some environmental issue (and the tetras getting it first). Eventually I managed to get him to eat and he seemed to get his food drive back, but after today’s water change I noticed a white growth inside his mouth:

It’s a bit blurry, but it definitely doesn’t look normal.
I hadn’t noticed this at all during his hunger strike, but maybe it was an internal infection that went external? It seems really well spread to have popped up overnight, and I never noticed any injury.
I don’t have a qt space big enough (unless I put him in a sterlite bin) if I had to medicate, but an antibiotic does look like the best answer here.
I’ll work on getting better pictures.

 

[Deadeye]

A tetra seems to be showing similar signs now- a white spot by its gill:

And the growth has spread throughout the jack’s mouth:

Is this at all consistent with columnaris? Or some other infection?

 

[Deadeye]

Bump

 

[kno4te]

Lymphocystis can do the same. Not sure if it’s columnaris. Would watch and hope to ride it out. Can salt the tank if the tetras are getting ich.

 

[Deadeye]

Good to hear - I didn’t even think about lympho. I’ll keep an eye out.
I don’t see any ich - the only spot on the tetra is a large ball like with the Dempsey.

 

[Deadeye]

Similar marks on a rainbowfish. Both rainbows have white on their fins as well.
Everyone else is about the same - the white is slightly spreading on each one.
Affected fish have an increased respiration rate, but nothing too drastic.
They all are eating - so at least a good sign.

 

[phreeflow]

Hard to tell from pics but my guess would be columnaris. Lympho generally doesn’t affect a bunch of fish at once. Columnaris, however, is very infectious.

 

[Deadeye]

Some better pics of the Jack’s mouth:

There’s also a few nodules along the gill - they can be seen in the forward shot.

 

[Deadeye]

I’ve started treating with kanaplex as of Monday - I just did the second round of treatment.
Since last week, the growth on the rainbow’s mouth has grown substantially (it won’t let me get a good picture) and the Jack is about the same.
Today the Jack started twitching and flashing, something seems to be irritating him, whether it’s a sign the infection’s getting worse or the medicine is working and breaking up a lot of the growth I don’t yet know.
The growth on the rainbowfish looks like it’s starting to separate/flake away, seems to be going in the right direction there.

 

[Deadeye]

The rainbow died:

I’m pretty much at a loss here. Given the death, I think it’s safe to say the bacteria is not responding to treatment, but I’ll finish out the course and see where it goes.