I agree with you Peter, in many ways, – but as I see it, – there is also another way to see this. When I find an attractive parosphromenus species in a shop, I must admit I buy as many as I can afford, and rarely settles for one or two couples. Mostly because I find it ‘vulnerable’ to have only one pair, – if one fish is lost, its all in wain.
So if its worth it (attractive species, good condition, etc) its possible to have one or two pairs for breeding, and a smaller flock as ‘spare’ so to speak, – and then I find it quite interesting to try to make a good ‘mixed’ tank with these fish.
I have done it for some time with my quindecims, – where I had 5 females and 1 male, – the four females were then in a tank with a few betta uberis and a lot of boraras, – that worked really well, and was quite attractive.
I also have a tank with parosphromenus anjunganensis, indostomus paradoxus and shrimps :).. that is also kind of interesting, although you dont see the indostomus paradoxus very much :).. they are the tinyer species here.
But I admit, its not always easy to make it work good. And breeding is really important first and foremost.