Yes, ROCKFISHES is a Scrabble word!

Letter values in Scrabble US: R 1, O 1, C 3, K 5, F 4, I 1, S 1, H 4, E 1, S 1.

Is it a valid word?

ROCKFISHES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the lean flesh of any of various valuable market fish caught among rocks
marine food fish found among rocks along the northern coasts of Europe and America
marine food and game fish with dark longitudinal stripes; migrates upriver to spawn; sometimes placed in the genus Morone

Also: striped bass, roccus saxatilis.