Unfortunately I lost a couple of the tetras. Water parameters have been fine and stable, no spikes. So I suspect this is due to plants decaying in the tank (I was hoping they'd rejuvinate...) - or possible . I've removed them and I've done few water changes. Since that I've - for the first time - I've seen the glowlights breeding!
I'm keen to have happy, unstressed fished that are within comfortable parameters, so have spent an unhealthy amount of time digging round and researching all this. Here's where I'm currently at...
Keep tank at 25'C. Stocking plan (will probably acquire them in this order, unless it makes sense to do differently):
Since I have a pond snail outbreak (hundreds of babies!), 3-4
assassin snails.
6 or max 7 corys - maybe a mix of bronze and sterbas, since they seem most suited to harder water (20 and 15DH respectively; the rest - save for pygmies - seem to want softer and/or more acidic water). I gather best to buy them all at once. I'm guessing with this number better to stick to two species rather than three (which would be a 2/2/2 or 2/2/3 split), rather than 3/3 or 3/4. I figure best to get these soon to get the sand moving.
Pearl gouramis (1M, 2F) My understanding is it's really either 1M, or a 1M plus 2-3F. I'd probably be happy with one, but sounds like they'd be happier as a small group.
Get c. 4 more
glowlights, so c. 11 in total (up from current 7). Happier and prettier in a larger swarm, no doubt. Though if any of the fry survive, I may not need to buy any!
Maybe
a bristslenose plec (irrational love, despite the mess!) (up to 20DH/268ppm depending who you ask). Ok to keep on their own, I understand/hope!
More crustaceans ... For plants treated with insecticide I gather it's best to leave them for a couple of months before adding shrimp to the tank. I may ultimate move my 5 amanos across too to the main tank and/or get some other shrimp (ghosts?); and/or maybe a dwarf crayfish (or more than 1? conflicting reports on what works best/terrirotialism); and/or Thai micro crabs. And possibly a large snail or two that would not be troubled by the assassins for clean up duty.
At the risk of overcomplicating this, I was wondering about some alternative/additional fish. As above, I'm drawn to the more unusually shaped fish (e.g. loaches, catfish, gobys), and (pearl gourami apart) more natural colours (particularly since this is an aquascape tank). So other contenders are (I guess as alternatives to corys and/or plec, I guess, else I may be pushing stocking) might be:
Loaches of some kind. Yoyos? A weather loach or few might be pushing it (prefer up to 12DH; conflicting reports as to whether a min number is 1 or 3+). Scared dwarf chain loaches would nip my tetras fins, given reports above, and I'd have nowhere to rehouse any of them...
Syno polli (just 1 ok?)
Dwarf lake / rift lake / false cuckoo synodontis - I gather ideally 4+. Possibly Might be a decent alternative to a shoal of corys?
Botia kubotai - I gather 3+, ideally 5/6.
Whiptail catfish
Might any of the above be a threat to the glowlight tetras?
Goby of some kind? E.g. Rhinogobius zhoui - gather min 4 (2M, 2F). c. 3cm. But prefer a bit softer water (216pm)...
Oranged Fin
Stiphodon (Stiphodon maculidorsalis) - gather I'd need 3 (1M, 2F). Grow up to 7-8cm. But prefer a bit softer water (216pm)...
Anchor catfish (kinda written these off as too small and unhappy with other bottom dwellers)
Finally, if I move the amanos, that leaves the 5g/19 litre tank empty. I'm planning on using that as a QT, until the main tank is stocked. In the longer run, I can see the sense in whatever ends up in there as being peaceful and compatible with the bigger tank, should I need to isolate/move back and forth/for fry etc. That probably rules out a tetra, so I'm thinking either shrimp (and maybe dwarf crayfish/collection of thai micro crabs) and/or least killifish (if I can find some). Though I might need a single sex group else risk being overrun with fry with noting to do with them, save add them to the main tank. I guess too small for frogs (and presumably bad tank makes if I do need to isolate fry). And as for celestial pearl danios, there are conflicting reports on whether a small shoal - maybe 6 - would be happy in 19L/5g, so probably best to err on side of caution and avoid. Still, I'm some months having to decide anything for that tank, so perhaps for another day.