How big before pulchra’s start pairing? My 5 are in a 120 cm and this is the dominant one for sure and at times he does this weird side to side swimming dance with some of the other ones but it doesn’t look like they are fighting. How big before pulchra’s start pairing? My 5 are in a 120 cm and this is the dominant one for sure and at times he does this weird side to side swimming dance with some of the other ones but it doesn’t look like they are fighting.