Let me explain(I have no photos),I live in the Midwestern USA.In Creeks and rivers,I sometimes turn over rocks,and there are Crawdads,and also a tiny long red fish.They look similar to algae eaters.I have seen these things for years and have no clue what they are called.I tried to catch one the other day,but they are too fast.What are they?

It is possible they are rosy red minnows. http://www.fishpondinfo.com/rosies.htm

They come in different colors, from almost pale white to bright pink/red. That may be what you're seeing.

Does it look like a Chinese algae eater or a plecostomus? If it looks like a CAE it is probably a member of the sucker family (Catastomidae). There are members of the minnow/carp family (Cyprinidae) that look a bit like a CAE as well.