I don't think you can look at a fishes shape or colouring and say these look simular, they should be in the same genus.
Some fish evolve to look alike through environmental factors yet they are completely unrelated.
South American eartheaters look very similar to some c/a eartheaters.They are completely unrelated but their environment and feeding strategy have dictated they evolved in a very simular way.
This is a good example of convergent evolution but does not make them of the same genus.
You're over simplifying my point which is based on Juans article which I happen to agree with... On the subject of Robertsoni... They were called the "false Firemouth"