Short fins may indicate female sex, but this characteristic should be combined with other evidence before sexing is conclusive.
Colors can change depending on the stress level of the fish. Female Bettas will be more colorful when stressed than non-stressed females.
Finding this spot may be difficult with younger females whose sexual organs have not fully developed. As the fish ages and becomes larger, the ovipositor tube will become larger and easier to see. If you are having trouble viewing the location of the spot, consider feeding or preparing to feed your fish. He or she will likely move to the top and angle himself or herself so you can more easily view the location.
Female Bettas will sometimes flare to show dominance too. However, they do so with less determination. Males tend to become obsessed with the fact that another male is near them. Do not leave the mirror in the tank for extended periods of time. While seeing your male Betta’s aggressive display is fun, this can stress your Betta to the point it affects his or her health. Male Betta’s fins, particularly, may start to shorten simply due to experiencing long periods of high stress.
Many pet store staffers are more knowledgeable about pets than you. However, their expert knowledge may be limited by their own pet interests. When consulting a pet store staff worker about the sex of a Betta, consider asking if they have ever personally bred Bettas, or if they have to look at the label before telling you if a Betta is male or female. When in doubt, assume the fish is male.
