As the fish approach adult size, tanks of 75-100 gallons are required to house a pair and subsequent spawns. Be sure to monitor the youngsters closely, as some are bound to wind up cowering in corners of the tank with torn fins and missing scales. It is a wise idea to keep these individuals around, however, because as the umbies in the original tank grow and spar, you may not be able to avoid sudden fatalities. Ultimately, you may need the previously beaten fish as breeders. Males begin to develop more blue spangling on the body and operculum, and the dorsal and anal fins will be slightly longer than those of the females.
Males also appear a bit more elongated in shape when compared to the stockier females.
Males should also have grown larger than females of the same age. If you're lucky, pair-bonding may occur between the largest male and his female of choice. You may witness two fish spending time together, patrolling a commonly-defended area of the tank. During pair formation the male displays to his consort, when not occupied with territorial defense. If she returns his displays rather than trying to escape his attentions, you can be fairly confident that pair-bonding is occurring.