fish vs shark

fish and shark both are nouns.

Word	Noun	Adjective	Verb	Adverb
fish	Yes	No	Yes	No
shark	Yes	No	Yes	No

As verbs, shark is a hyponym of fish; that is, shark is a word with a more specific, narrower meaning than fish:

Other hyponyms of fish include crab, seine, scallop, scollop, rail, brail, angle, shrimp, net fish, trawl, still-fish, prawn.

fish (noun)	shark (noun)
any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills	any of numerous elongate mostly marine carnivorous fishes with heterocercal caudal fins and tough skin covered with small toothlike scales
the flesh of fish used as food	a person who is unusually skilled in certain ways
	a person who is ruthless and greedy and dishonest

fish (verb)	shark (verb)
catch or try to catch fish or shellfish	hunt shark
seek indirectly	play the shark; act with trickery