Hi drrobertprice Ph.d in ichthyology and herpetology and new member. I breed Flowerhorns, Green Terror Cichlids, and Gold Queens. One of the most reliable way to sex flowerhorns at about2-3 inches is the appearance of a black spot in the dorsal fin. Unfortunately this is only about as reliable as humps. Some females have humps, and a small number of males have black dorsal spots. Males are thicker than females of the same length, and generally more colorfull. Be happy you dont have Rose Queen breeders. I know of no way to be sure of sex in these except checking for genital papillae.