you will find that bass, redfin and smaller yellas/silvers will school.
all of these fish can also be found on their own too but out of all the freshies they are most likely to be found in schools.
larger yellas and murray cod will tend to hang around a particular snag.
thats why you will often hear of people pulling the same cod year after year from the same log or hole.
This can also be true of river bass, although migratory they do tend to hang in certain areas around snags and bankside cover.
so there you go, if i was fishing impoundments for bass and reddies I would purely rely on a sounders ability to find the schooled fish or work original creekbeds or points. where as if your fishing for yellas/cod then try to work steep rocky points, ledges, boulders and areas of submerged timber.
good luck with it all, im sure you will get the hang of the freshies