Restocking A Slightly Acidic, Softer Water Planted Tank

How small do you want to go? If tiny (15 to 20 mm) would be OK, how about Microdevario kubotai These are green fish from Thailand and Myanmar, so they'd fit 'no more red' and Asia. And they like soft water. They are sold as green rasboras or green tetras.

I saw them a few months ago and again a couple of weeks ago in the LFS. Both lots are much more the size of neon tetras than as small as Sue's experience - and I've read that this size variation is commonplace on quite a few sites. Incidentally, last time round they were described as 'neon yellow rasboras' although actually luminous green https://www.fishkeeper.co.uk/databank/neon-greenyellow-rasbora-. [The term 'green tetra' may be confusing as there are several which might fit that bill - green-coloured tetras https://www.fishkeeper.co.uk/databank/rathbuns-bloodfin-green-fire-tetra and blue-green-coloured tetras http://www.seriouslyfish.com/species/paracheirodon-simulans.]

I think I need to go and see them in the fish shop.

They do look attractive option, but I am concerned about their size. I think they should be ok with my shoaling fish - the dwarf rainbows seem to be on the limit of size and my harlequin and espeii rasboras are actually recommended by seriously fish as suitable companions. But if i put celestial pearl danios or axelrodi rasboras (both a similar size) into the CC, I get red warnings about them and both kuhlis and kribensis.

I don't think the kuhlis would be a threat because their mouths are actually really small.  And I don't have kribs yet. Also they live in different parts of the tank, as I understand. But one of the attractions of kribensis is to have something a bit different and bigger than the rest of my fish (as a sort of specimen species). So I'm not sure about going smaller than the espeii rasbora.

Apart from tetras not being Asian fish, any thoughts on penguins, Black neons and x-rays ?

Thank you.

Having found this article I will persevere with finding an Asian shoaler!

https://www.practicalfishkeeping.co.uk/blog/articles/2016/11/18/social-acclimation-the-next-thing-in-fishkeeping

It's also made me wary of increasing my existing shoal sizes - of dwarf rainbows and harlequin rasbora!

This is looking like a good contender:
http://www.seriouslyfish.com/species/brevibora-dorsiocellata/

I thought it was a recommendation from here, but can't find the comment! Finding it might be the challenge. EDIT: I've just found it on MA website: https://www.fishkeeper.co.uk/databank/emerald-eye-rasbora

I will also have a look at the green rasboras. 

Just reading about ricefish and found this:
"was the first vertebrate animal to mate in space during the mid-1990s"
 

Not really a requirement for my tank! 

I have good international relations in my tank - x-ray tetras and harlequin rasboras.

The x-ray tetras' daytime is probably split 25% in each of the following modes, from early morning, late morning, afternoon, evening: the males having quite vigorous spats while the female rests elsewhere (and occasionally a harlequin joining in); a female being chased vigorously by all the males, esp through the plants; quiet times when they rest at particular "staging posts" in the tank, usually in the lower third; playing and swimming together with the harlequins, esp in the filter flow, inter-shoaling as though all one species.

The harlequins' daytime is less varied and tends to be split 50%, 25% and 25% in morning, afternoon and evening respectively as follows: quiet times whey they rest at particular "staging posts" in the tank, usually in the upper half; one male harlequin taking possession of the middle 50% of the tank, chasing anyone (irrespective of species) who enters that territory round the tank at speed and into a corner / two males (I think) displaying against each other; playing and swimming together with the x-ray tetras, esp in the filter flow, inter-shoaling as though all one species.

I suspect the afternoon behaviour of the aforementioned harlequin is just unusual, while the spat behaviour was learned from watching the x-ray tetras in which one tries to get involved occasionally.

At night, once the light goes off, there's a bit of re-positioning in which they shoal up with their respective species but a bit of manoeuvring takes place, generally resulting in the x-ray tetras at mid-level and the harlequins in the upper third ie each species slightly higher up than their daytime resting positions.

I didn't mention rice fish although I have Daisy's ricefish (Oryzias woworae) because their hardness range has 5 dH as their lower end.

I've kept M.kubotai in the past and I'd say mine were the same size as the ember tetras I had in the same tank. The biggest fish I had them with were Apistigramma cacatuoides, and the male is quite a big fish for a dwarf cichlid.

I'd have to give a massive +1 for Pristella Tetras (X-Ray Tetras), which are probably the favourite fish of mine to date...  I have 12 of them and they seem super peaceful and playful, sometimes shoaling with the Cardinal tetras just for the fun of it...  Great fish indeed and I'd gladly have more of them... 

Just had a look on SF...  They look really nice H...