Question

dorsal fin
pectoral fin
pelvic fin
anal fin
ventral
gill slits
dichotomous key start over
question 1: does the specimen
have a jawless, circular - shaped
mouth?
yes: lamprey
no go to question 2.
what is the fishs species?
retry

Explanation:

The fish in the image has a jaw (not jawless, circular - shaped), so we answer "No" to Question 1 and move to Question 2 (though not shown here, the fish's appearance with both eyes on one side and the fin structure is typical of a Flounder. But from the first step, we know it's not a Lamprey. If we follow the dichotomous key, after answering "No" to the first question, and considering the fish's morphology (flat body, both eyes on one side, various fins labeled), the species is likely Flounder (though the key here starts with Lamprey as the first option, the fish shown is a flatfish, commonly Flounder).

Answer:

The fish's species is likely Flounder (or a type of flatfish; if we assume the dichotomous key continues, but from the given, after "No" to the first question, the fish shown is a flatfish like Flounder).