I used an aquaclear hang on in my 29g and I use one in my 20g tank. Perfectly acceptable and doesnt require a sump and all that stuff. LOL
A mandarin is a gamble even if you do have the sump and pods
and all that stuff. I currently have an ORA mandarin and a scooter, I was really really lucky in that both now eat frozen food. But it took almost a month and the only thing that kept them alive was that I had a good population of pods
. They both could suddenly one day refuse the prepared foods as well so theres some more of a gamble.
I love my Mandy, but not sure if I would take the gamble again.