I haven't done any realistic drawing since college art classes 25 years ago, preferring instead goofy, unrealistic cartoon stuff like woolly buggers with ping pong ball eyes. So when asked recently if I ever did realism I decided to try a sketch to see if I still had it in me, or whether I'd lost my grasp on reality.
Whimsical, yet poignant. You could start a whole series of soon to be mythological fishes, perhaps a three-headed chum (aka dog) salmon (from Cerberus the 3-headed guard dog of the underworld).
If I may make a minor suggestion, the format for scientific names capitalizes the first letter of genus name (Onchorhyncus in your drawing) and uses lower case for species and subspecies (mykis mythologicus). And because these are foreign words, they would be in italics or underlined to indicate that as well.