What's happening to my M Kubotai...?

[Bradders]

Okay not ideal but I’ve had to catch two of them and pop them in a glass to get a clear picture.

Does the fish on the right look like the tail is arching down, like a curvature of the spine?

 

[Slinky1]

Does the fish on the right look like the tail is arching down, like a curvature of the spine?

No I see what you mean but I think that’s just the curvature of the glass. The school has no change in behaviour, confident and feeding well but I’ve pulled the 4 I thought I can see white on the fins. The last two had definite slow behaviour. I’ve spend hours watching them and the 16 I have left are indistinguishable except that I picked out four with suspect white bits (two of which I photographed in the glass). I’m happy to catch all of them for a photo but not too keen to stress them unduly if that last picture shows what I see.

Attached is another of the school in the main tank which I can’t see anything wrong with currently.

Sorry, they really are incredibly fast.

 

[Bradders]

Thanks for doing that. To be honest, it's quite hard to fully pinpoint an issue.

Currently, you have (on the whole) normally behaving fish, normal eating fish, with four that are showing some light signs of fungus-related symptoms. (It's hard for me to see that as well with any degree of clarity). If I had to have a stab (and I do mean a stab!) I would say some bacteria related and possibly Columnaris - but I feel very uncomfortable suggesting that due to it not 'leaping out' at me.

Your tank seems to have a few plants (would you say low, medium, high plant mass)?