Hi, my Betta is in a 28l cube with my 2 ADF. It is obviously heated and filtered. I am being somewhat criticised on another forum as "28l (25l with displacement) is too small for anything but shrimp". This has made me doubt myself and I'm feeling a little upset that I may be being unintentionally cruel. I know people's views on minimum tank size varies but is this really so small as to be cruel for a single Betta and 2 frogs?