In reference to a recent post by dankfishtanks called something like Sub Adult Vieja ID, I referenced the Aqualog book (and cichlidae.com) before venturing what I suspected was a decent answer, 
In Aqualog there are 4 photos of hartwegii, a juvie, a young male, a mature male, and a female.
Info states where it is found, (counties, river system)and estimated size.

In Aqualog there are 4 photos of hartwegii, a juvie, a young male, a mature male, and a female.
Info states where it is found, (counties, river system)and estimated size.

I like the Ad Konings books for ID, lake maps and such.