Yes, GUDGEON is a Scrabble word!

Letter values in Scrabble US: G 2, U 1, D 2, G 2, E 1, O 1, N 1.

Is it a valid word?

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

small spiny-finned fish of coastal or brackish waters having a large head and elongated tapering body having the ventral fins modified as a sucker
small slender European freshwater fish often used as bait by anglers

Also: gobio gobio.