Yes, BONITO is a Scrabble word!

Letter values in Scrabble US: B 3, O 1, N 1, I 1, T 1, O 1.

Is it a valid word?

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

flesh of mostly Pacific food fishes of the genus Sarda of the family Scombridae; related to but smaller than tuna
fish whose flesh is dried and flaked for Japanese cookery; may be same species as skipjack tuna
any of various scombroid fishes intermediate in size and characteristics between mackerels and tunas

Also: oceanic bonito, katsuwonus pelamis.