First one is Nimbochromis venustus.
The other two are a little more difficult to say.
The blue one looks like a Copadichromine. You'll have to sort through some profiles and see if any match up. Hybrids are always a possibility, especially with the popularly mixed "electric blue" types.
The solid silver fish looks very much like a female or subdominant male version of the blue fish. Does it ever show a pattern?