I am under the immpression they are spilo cf since they have what I think are serra specidic genes such as the dorsal fin pushed back, the pointy face and the mean demenior, I also thin that we purchased the fish from the same person
the odd thing is that i have 6 in a 20 gallon that are about 3 inches now and they all get along good...
i still think they are CF tho
but i havent ever had any other fish except pygo so hey take my advice with a grin of salt
also , mine might be bigger but mine have ALOT more red on their gill plates and chest