This is an interesting fold, eyes similar to the Ryukin and some similar tuck, pleat/squash maneuvers to gain a multitude of layers and stickey-outey parts in very particular places.
The fold was fun because I found it difficult to guess what would be come what. The body shaping is very dense, I suspect this will be a torturous little fish to fold small because of the subtly rounding to make the body appear plump and aquiline.
Lots still to try, will interleave folding and real life (as it should be).
Efficiency of sheet usage here is interesting, so much of the paper is devoted to fins that the body ends up smaller, but looking to similarly scaled models it still looks quite natural.