For most hobbyists, the male Flowerhorn is preferable to the female because of the different traits and behaviors they exhibit. For example, the male has big nuchal humps. In Chinese Fengshui, these are believed to bring good luck. Moreover, the males are more attractive. They have more vibrant colors, and their bodies are much broader. Females tend to be much smaller, and their features are far less attractive. However, if you’re interested in breeding your fish, you must have both sexes in your tank.
In order to get the Flowerhorn sex you really want, hobbyists are advised to purchase a fish of 4-6 months of age. This way, the sex of the fish is able to be determined. There are, though, various sexing methods at any age. The table below summarizes the these methods according to different life stages of Flowerhorns.
Sexing of Flowerhorn fish at different stages
| Age and length | Characteristic | Sexing Method |
| 2 months(1mm – 30mm) | . Juvenile stage.. Colors and body patterns are not noticeable. | . No known method. . Observations shows larger sized fish within the same batch tend to be males. |
| 2 – 5 months( 30 mm – 150 mm) | . Colors and body patterns are becoming more distinctive. | . Distinctive black marking on the dorsal fin indicates that it is a female. However, this is not foolproof. The same pattern does exist on some male Flowerhorns..Observations on the shape of the genital papillae. V-shaped papilla indicates a male fish, while a U-shaped papilla indicates a female fish. Gently squeezing the abdominal region may reveal the papillae..Male Flowerhorns will have broader body with higher dorsal, anal and caudal fins. It is also observed that male Flowerhorns will have thicker jawline and more distinctive body color. |
| 5 months and above(150 mm – 600 mm) | . Flowerhorns begin to mature. Distinctive and rather prominent head humps are visible on the male fish. | .Female will start to lay eggs even without the presence of a male. |