Mono Or Braid?
 

long time user of mono i have 100% swithched over to braid while cod and haddock fishing on stellwagen bank. the no stretch factor especially in the deep water is critical. eighty pound test, brand is up to you, 450 feet connected to dacron backing will do. haddock bites are very light and the braid gives you that sensitive touch. good luck! best, capt. jim