Here is a video of one of my embers https:///youtu.be/UFx92wsmMjM - just insert or copy & paste the url into the search bar to view it. [Please excuse unsightly water marks on tank's background/wallpaper.] She is breathing fast but the only other sign of anything untoward is a ?protrusion (albeit not through flesh) of ? internal organs. If she weren't breathing fast, I'd probably just assume the ?protrusion was natural variation.
However, some of the microdevario kubotai I used to have ~5-6 years ago often resembled this until ultimately the flesh 'opened up'. I did wonder at the time if fish TB / mycobacterium was present - I had elderly x-ray tetras and harlequin rasboras, many of whom were developing spinal deformities (but, having consulted a fish expert at Practical Fishkeeping, impossible to definitively say without a post-mortem whether simply old age or fish TB) and I also wondered if the filter output flow had been too strong and contributory to or causing this or the MDKs' concurrent scoliosis as viewed from above and post-mortem.
I can eliminate strong filter output flow as a cause/contribution - I've been using a softer output flow via a spraybar in recent years, and certainly pre-existence of embers. In the last few months, I have had two other fatalities - one of the adopted cardinals (whose full background/age/heritage I'm not fully abreast of - likely columnaris which that species seems most prone to IME) and an espei rasbora (sudden decline over the course of a week - concave belly, 'knifeback' appearance, bent spine and skinny when viewed from above) but my instinct is that these are each isolated.
Thoughts welcome on:
* is this a 'protrusion' I'm seeing, or just natural variation?
* as water quality is optimum as per usual, is there anything I can do?
I'm reluctant to isolate her in the QT (unless *absolutely necessary*) as, IME, it seems to do more harm than good.
[PS. For own protection, weekly fishtank maintenance regime in recent years has involved full-length plastic gloves*, safety glasses and surgical mask in the event of splashes. (* also for any additional fishtank tinkering.)]