for alliance, you can fish from the safety of menethil harbor and get oily blackmouths and firefin snappers at the same time.
it may be due to chance but i've gotten about 20 firefins in 30-40 minutes. i time myself in a way because i use those +fishing items..so usually i fish about 30-40 mins at a time. that's about all i have the patience for. so being in the harbor with a fisherman supplies NPC nearby, i can easily buff my fishing pole, thus allowing me to get an estimated amount of time that i fish.