A good fisher knows what fish he has on his line before he pulls it up based on the bait, location, ! or !!!, and way the rod works. Some fish are similar, but its very easy to avoid items.
@Stolas: I guess you're right, but, both me and my friend were using the same rod and the same bait (which besides I checked and were the right rod and bait to use in that place). He barely reeled up items, 95% of what he fished up were actually fish (and he didn't let fishing go depending on the message, we were fishing in the exact same way), while 95% of what i fished up were items... Was like wtf? °_°