How to Determine the Gender of a Betta

Known for their bright colors and flowing fins, betta fish make a beautiful addition to your fish tank or aquarium. Unfortunately, bettas can be finicky about their tank mates. Having all males in one tank may create behavioral problems. Having all females cuts down on the aggression, but prevents any baby bettas. Identifying male and female bettas not only aids in the breeding process, but also helps you avoid aggression issues that arise in an unbalanced aquarium.

  1. Colors

    • Typically, the male betta has a richer, more vibrant color than the female. Placed side by side, the female betta̵7;s coloring often looks dull in comparison to the male̵7;s coloring. However, while the difference in colors used to be a primary method of determining gender, breeding practices in recent years have produced female bettas with colors nearly as vivid as male bettas. Because of this, gender identification based on color alone is often unreliable.

    Fins

    • While young bettas have similar fin sizes, a pronounced difference exists between adult male and adult female bettas. The ventral fins--the ones resembling arms--of male bettas are longer and thicker than those of the females and tend to have a more pointed appearance. The dorsal and anal fins are also longer and thicker on males than on females. In some females, the caudal fin at the end of the tail has a slightly rounded appearance.

    Egg Spots

    • Adult female bettas have an ovipositor, known as an ̶0;egg spot,̶1; located between the ventral and anal fins. The spot looks like a white dot, approximately the size of a grain of sand. Occasionally, young male bettas also display this spot, so it̵7;s only a fair indicator of gender on adult bettas.

    Beard

    • Flaring is an act of aggression in bettas and occurs when the fish feel threatened. When a betta flares, it turns its gill covers out, stretching the membranes to resemble a beard and making itself appear larger. The beard on male bettas is much larger than on females. In fact, on many males the beard is large enough to be seen even while the fish isn̵7;t flaring.

    Behavior

    • Male bettas are generally far more aggressive than females. Females rarely show aggression, but males fight to establish dominance over their territory and the females present in the tank. The aggression of male bettas often proves fatal to other males in the tank; this is why bettas are often referred to as ̶0;fighting fish.̶1;

    Body Shape

    • Male bettas have slightly slimmer bodies than females, as well as a less rounded appearance. Female bettas are usually slightly shorter than males; however, the differences in body appearance are sometimes so slight that gender identification is difficult.