When the cut-throat isn’t occupied in crime,
He loves to hear the little brook a-gurgling…
-Sir William Schwenck Gilbert, The Pirates of Penzance
I’ve been thinking about the slash.
Maybe it’s about dominance. Or attraction between the genders. Or identification. Or a warning.
It’s not camouflage. It can’t help the fish swim faster or find food more efficiently. It doesn’t mean they’re poisonous. It’s just a striking pigment variation that occurs beneath the gill plates which underwater would never even be seen by other fish.
The more I think about it, the more convinced I am that the slash exists for me.