As an update on my aquarium over the past ~9 months or so (following the huge but ultimately unsuccessful efforts to attempt to save my cardinal tetra that put up such a brave fight):
* her friend developed a white fleck on her tail and then a white growth from her mouth, that I tried treating with eSHa 2000, Waterlife Myxazin and Maracyn-2 at various stages (Apr, June, July) when the situation seemed to worsen (eg fungus, bulbous), but unfortunately any success was limited and not long-term, and ultimately she succumbed in Sept;
* the ‘runt’ cardinal became very weak / suddenly developed buoyancy problems and spent a week or two alternating between lying on his side on the tank floor and darting around, or hovering under the spray bar (presumably for O2), but ultimately succumbed in early Oct;
* as the remaining fish were all very robust, I then increased numbers of each of the two species to 5 espeis and 7 cardinals (from 2 and 4) – think the espeis were pleased to acquire some shoalmates;
* very happy with just the two species in the 54L tank - in hindsight, looking back on videos of the fish during the “original cohorts dying off / new stock” phase when I had small numbers of 4 species in the tank at once, that isn’t an approach I’d take again but instead wait until all have passed away before adding new ones;
* two nerites are both alive despite the male one having regular seeming near-death-experiences;
* hygrophila guanensis is still alive (almost 2 years!) – and propagating regularly! All in little terracotta pots – an aquascaper’s horror (sorry, Matt) but works for me and the tank inhabitants.
Merry Christmas and a Happy New Year, all.
https:///youtu.be/IG799_scnM8