i sometimes do, like if the fish is paticularly special to me it probably has a name for example:
my lmb: wally
my lsn: vapor
and my barramundis name was steve
Only those with 'personalities'. The Danios and Corys don't have names but my Black Ghost Knifefish is named "Shadow" and my Angels are "Bippity, Boppity, And Boo".
I only have a couple of named fish, which are fish I was attached to for some reason or another, usually just that they are favorites. Currently I have a dempsey named Jean-Baptiste (I didn't name it, but still call it that), a 3 year old blind cave tetra Stevie (as in Stevie Wonder), and a buffalohead called Buffy.