3 - 4 centimeters.
The adult body length of neon tetra fish is usually 3 - 4 centimeters. They belong to small - sized tropical fish. The following is a detailed analysis:
Body characteristics.
According to authoritative encyclopedia information, neon tetra fish are small and narrow - bodied. Generally, their body length does not exceed 4 centimeters after reaching adulthood. There is a neon longitudinal band on their lateral line, and the caudal peduncle is bright red. The overall color is bright, but the body size remains mini.
Comparison with other tetra fish.
The glass tetra fish mentioned in the search results can reach a body length of 4 - 5 centimeters, while the neon tetra fish is smaller, further confirming its small - sized characteristics.
Growth stages and reproduction.
Neon tetra fish reach sexual maturity at 6 months of age. At this time, their body length is close to the adult size. The best breeding period is from 8 to 10 months of age. At this time, their body length is stable within the range of 3 - 4 centimeters.
Summary: Neon tetra fish have become a popular choice in aquariums due to their small size and the beautiful "fireworks - like" appearance when they swim in groups. However, attention should be paid to their suitable water temperature (22 - 26°C) and weak acidic soft water environment to maintain their healthy growth.