Unless a fish happens to wind up in your net they are not easy to identify without experience. Once this is done and you are relatively certain of the type you can note which fish you see. Not all the possibilities are given here. This should specifically note barriers within a short distance of your monitoring site, not those more than a mile off. This indicates runoff problems.
Most streams are clear in periods of low flow.
A tea color often indicates the presence of tannins in the water from decaying leaf matter. A colored sheen may lead to an oil spill of some kind. Otherwise discolored water indicates erosion or other types of runoff upstream from your site that could lead to lower or changed macroinvertebrate populations. In most riffle monitoring the bottom will consist of gravel, cobbles, and boulders. In some cases there is a layer of muddy material between the cobbles that may increase of decrease through time.