Hey 77,
You are truely a great photographer...I must give credit.....the micro-focus is so clear...the mouth...the eye....the nostril.....the scales...... and the only point that is out of focus is the most important....the infection site.
Just a joke brother...but is true..see for yourself.....what happened?
Anyway, this is very common both in discus and in angels and is caused by encapsulated parasite (especially bacteria) breaking free and the whitish thread is the byproduct (waste) of the feasting of tissue.
At a point in time, some of the bacteria were able to penetrate the epidermis during stressful and suboptimal condition but the body was able to encapsulate some of them, preventing further attack. The immune will keep on building tough walls around each or a group of bacteria preventing them from causing harm or escaping...thus forming nodules which are not visible with the nake eye. You may also find these nodules in the intestinal wall and spleen.
Now, there must be a drop of the water quality (suboptimal condition or/ and stress) and weakening of the immune to allow the encapsulated bacteria to proliferate.
'Mycobacterium (TB)' bacterium is usually found together with this problem...but not sure whether it is the primary culprit.
To the solution...nothing much you can do except these:
1) Do 3 x PP treatments with a week to lessen the total paraite load in the tank. Also this will oxidize any bacteria in the tiny open-wounds that are exposed to the PP treated water.
2) After the above, treat the fishes with metronidazole (as it is also effective against certain bacteria) for 12 days @ 1.5 gm per 100 litre of water.
Try and see how,
Andrew
