The adult length of betta fish varies depending on their species and rearing conditions. Details are as follows:
I. Length Range of Common Betta Species
Chinese Betta (Betta splendens)
Wild individuals typically measure 5-10 cm, while those under artificial rearing can reach approximately 7 cm.
The tailbar betta (a subspecies of Chinese betta) is slightly longer than the roundtail betta, but neither exceeds 10 cm in length.
Thai Betta (Betta splendens var.)
Wild specimens are about 5-6 cm long, and captive-bred ones can grow up to 8 cm.
They are known for their broad fins, but their overall body length is generally shorter than that of Chinese bettas.
Three-Spot Betta (Betta trifasciata)
It is a larger betta species, with a maximum length of up to 16 cm.
The common length ranges from 7-12 cm, and they are distributed in Taiwan and low-altitude water areas.
Forked-Tail Betta (Betta imbellis)
Adult fish measure 7-10 cm in length and are found in southern China and Vietnam.
II. Key Factors Affecting Length
Species Differences: For example, the three-spot betta (16 cm) is significantly larger than the Thai betta (8 cm).
Rearing Conditions: Scientific feeding (e.g., water temperature of 24-27°C, pH of 6.5-7.2) can promote growth.
Age Stage: Bettas reach sexual maturity at around 6 months old, and their length stabilizes once they become adults.
III. Special Cases
A very small number of individuals may exceed the species' typical length limit under ideal conditions (such as large water volume and high-protein feed). For instance, some Chinese bettas can grow to 12 cm, but such cases are rare.