It’s a very interesting thread – thank you, Sverting, for posting the link to the article on “seriouslyfish”.
I keep all my fish at room temperature – this means, at around 21°C water temperature in winter – in summer it increases to about 26°C. No filters, only additional light during the darker months/hours of day. At night the temperature drops to 19°C in winter, that’s the minimum water temperature I noticed.
I keep Dario dario, Pseudosphromenus dayi, Badis kanabos and Badis singenensis, Boraras maculatus and B. brigittae and Danio margaritatus at these temperatures – and my new P. nagyi too. Dario, the Badis species and Danio bred (and still breed) successfuly, the Pseudosphromenus are still young, but already spawning. I’ve also seen the Paros spawning – it might still have been sham pairings, but still!
I am convinced my fish are doing quite well with these temperatures.