Which Carpa koi breeds come in Nero?

Club breed standards describe Nero for the Koi.

Carpa koi color

Nero

Solid black pigment. In birds often with a green or purple sheen; on skin, legs, beak, comb and tongue the dark pigment some standards call for.

8 Carpa koi breeds list Nero. It is in a club standard for 4 breeds.

Breed	JNPA
KoiSanke	Da standard (“black imprints (urushizumi)”)
KoiShowa	Da standard (“black body (black background)”)
KoiBekko	Da standard (“black imprints shaped like spots”)
KoiUtsuri	Da standard (“black body (black background)”)

How Nero can appear or change over an animal's life.