bluey is a very good bait, as has been said it gives off a big oil slick.
u can use it as a tipping bait 4 flats & whitties they go mad 4 it, or u can use a fillet of bluey wrapped round a crab, mussel, squid, razor, lug or rag bait 4 cod but flesh side out.
or use a whole bluey head & tailed on big pennel rigs 4 big cod & conger.
only thing u need do is use it frozen or just part frozen,if left 2 fully defrost then it goes 2 mush & its much harder 2 bait up. i carry fillets in a 2nd food flask.
bill