Do remember this, Identifying a fish is not always that easy and just because you think he is a fish he may not be.
Also identifying fish is only part of the equation. In cash games we can use it as part of our table selection process. Like if there is no fish, we leave, and if a table has several fish, we try to get on it. But boyond that, what are you actually going to do different, if someone is a fish? If you cant answer that, then identifying player types is sort of pointless. And fish are not only fish. Some are more on the passive side, and others are more on the aggressive side, and the best way to adjust to these players is not the same.
To give a simple example referring to HUD stats a 61/5 and a 61/38 are both fish, because they are both playing far to many hands. But if I open AJ and get 3-bet by these two players, the way, I react, is totally different. Against the 61/5 (whale) I will give strong consideration to folding, because when this player finally takes an aggressive action preflop, he likely has a very strong hand. Maybe I put him on a range like AK and QQ+, and that range has AJ crushed. But against the 61/38 (maniac) I will most likely 4-bet with intentions to stack off, because his 3-betting range can be anything remotely playable.