From my merchant I got a little Mesonuta as a by-catch from some Nannostomus trifasciatus from Brazil. First I was not sure, which species it is, but now I am pretty sure, that it is a Mesonauta insignis. He is about 5cm big and sometimes he is a little bit aggressive against the same sized Andinoacara. biseriatus, what I did not expect.
If something new happens, I will write here.