The black fish looks like a male redear sunfish to me. Often centrarchid males get much darker before and during spawn. Particularly in clear water where it probably serves to protect the male protecting the nest from being spotted by avian predators. So are redears about to spawn in your area? If so, this may be the reason it is so dark in color.

It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers