Males will be larger yet more slender. They exhibit numerous small spots in their unpaired fins. More body spangling.
Females will be smaller yet stocky. Many exhibit markings in their dorsals. They develop a large, round, bright red belly when "in the mood"
Male frenata:
Note the small spots in the rear part of the anal & dorsal fins and in the caudal fin. More body markings. Another method is the "muscle striations" along the abdomen.
Female frenata:
Clear fins. Less body patterning. No "muscle striations" along the abdomen. If she were ripe her belly would be bright red.