Some of my fish have names; they usually just occur or happen by accident like 'Mrs Whippy', my Royal whiptail, who got called that because she deos lash my ram around with her tail sometimes (the ram is obsessed with her and follows her round; it would drive me loopy too!). My angel is Gorky, after Arshile Gorky, the artist (his biography was called 'Black Angel')
Some of them have collective names; my green neons are called 'Bob' (yes, all of them! We can't tell them apart, can we?!), the tiger barbs are called 'The Swarm', because they're dangerous in a mob and stripy like bees
My kids have named some of the others; the oscar is 'Gormok the Impaler', named by my son after a WOW character; the striped talking catfiah is called "Six" (we had one called 'Five' 'cos they have a 'V' on their heads, which is the Roman number five

he died, so this one is, "the one after Five"); the Synodontis is 'Half Tail', for obvious reasons (he was like it when I got him; it's never grown back). The BNs are Russell and Lady Eleanor.
None of the others have names.