I use this site a lot when setting temperatures. I find it very useful.
I’d like to agree with the article this topic started about. I keep my Betta, paros and irrubesco puffer at slightly higher than twenty degrees. They all do fine. Only Betta strohi seems to really need high temperature. When I dropped temp to 22 degrees they started to look really bad very quickly. When I put it to 24 it got a little better, but now I keep them at 26 degrees. So it doesn’t go up for all fish. Still, it is very good not to believe everything they say, but think for yourself and look at how nature does it.