Pregnant female betta fish (with Siamese fighting fish as an example) exhibit the following typical characteristics, which can be comprehensively judged through multiple dimensions:
1. Changes in Abdominal Shape
Significant Distension: The abdomen bulges into a spherical shape, with a diameter ranging from 30% to 50% of the fish’s total body length. It feels soft and elastic, resembling a "small glutinous rice ball."
Protruding Reproductive Pore: A white, semicircular protrusion (the reproductive pore) can be seen on the lower abdomen. When gently pressing the abdomen, egg-like bulges may be observed.
2. Body Surface Traits
Appearance of Breeding Stripes: During the breeding season, vertical stripes of varying shades (known as breeding stripes) appear on the sides of the body. In some individuals, the abdominal color brightens or turns dark brown.
Body Color Changes: Some female bettas experience a lightening of body color, or develop melanin deposits (e.g., at the base of the caudal fin).
3. Behavioral Performances
Reduced Activity: They swim sluggishly and often hide in shelters, displaying behaviors similar to "nest-building."
Decreased Appetite: In the 3 to 5 days before spawning, food intake decreases by 40% to 60%.
4. Breeding Preparation
Accepting Male Courtship: Mature female bettas will actively approach males; if not pregnant, they may be chased away by males.
Nest-Building Behavior: Male bettas blow bubbles to build nests, and female bettas may participate in interactive behaviors related to this process.
Note: The abdominal distension of female Chinese betta fish may not be as obvious as that of Siamese fighting fish. A comprehensive judgment should be made based on their behavior and reproductive pore characteristics. During the breeding season, it is recommended to maintain the water temperature at 28°C and provide high-nutrition food.