I was looking into the different fish, and even other ingredients used, in the production of sushi to see if there was a purple element that would stand in for the purple of the E4 logo. I was unable to find such a thing, closest to what I was looking for would be tuna but that’s really more of a dark magenta/maroon and not nearly as vibrant as I would like.
I was actually only able to find one purple fish and it isn’t even edible: the Purple Queen Anthias. I also thought, going back to my primary school history lessons, of the purple secretion produced by several species of rock snail that is used to make tyrian purple dye. Just as the purple fish are inedible, I don’t find the idea of sea snails to be a particularly appetising one (not that purple sushi would ever be particularly appealing). It’s not an issue, however, as I never wanted my animation to be 100% accurate. That being said, I’d rather create a fantasy create for my animation than use a specific yet obscure and inedible one; I feel it falls more in line with the E4 aesthetic.