I used a certain type of barbecue sauce for meat that contains anchovies. If the fish content is more than 1.66 percent (not batul b’shishim) will the meat be categorized as a meat/fish mixture which consequently would be a sakana?
Correct, the sauce should not be used with meat, and this is the reason that the OU has OUF for fish, to let people know that it should not be used with meat or chicken. Even if the sauce was already put on to the meat, the meat should not be eaten. The truth is that even if it would be less than 1.66 percent it would still be an issue since the fish is there in order to give taste, it needs to be botil in a lot more than 60.
Pesachim 76b, Y:D 116-2, Aruch Hashulchan Y:D 116-10, Kitzur Shlchan Aruch 39-1, Kaf Hachayim Y:D 116-18, Nikudas Hakesef 116-2, Chochmas Adom 68-1, Shevet Halevi 3-103(4).