We don't have names for most of them, since we have multiples of most of our fish, plus we got really attached to our first fish, a male Betta (he died from dropsy 4 months later it was awful) and we named him, so we try not to get too attached anymore and not naming them helps.
But... our male guppy I call him gupp gupp. Our bn pleco is called Mr. Algea, and our female betta is Miss Fish or Miss Betta. The male betta is my mother in laws, and he is called Red
Everyone else is just called by their fish name. We have 1 amano shrimp that is smaller than the other 5, and he is a bit mean to the other shrimp sometimes, so, we call him little a****** sometimes. lol.