I only rarely will name my fish, in great part because it's difficult to easily spot just one fish in a school. Sure, if all the neons are together it's easy to pick out the largest and smallest, but if they're scattered? Not so easy.
Singletons stand a better chance of getting names, but even then I tend to just mentally tag them by their species name or a specific characteristics. Maybe it's just that I live alone-if you mostly only talk to yourself about a fish, a mental image works just as well, if not better, than a name.
The only recent exceptions were my angelfish Fred, whose name is a bit of a joke as I got tired of people asking me what I'd named a fish so I just referred to EVERY fish newly added as "Fred" and my last betta Pez: a lovely but pathetically not well Petco veil tail that I bought on something of a impulse to have as a poop dispenser in my no-tech plant holding tank.