8 to 16 months.
According to the Fish Encyclopedia website, clownfish can grow about 0.5 to 1 cm in a month. Because they are small, they won't grow too much. By calculation: 8÷1=8, 8*2=16, it therefore takes 8 to 16 months for the clownfish to reach 8 cm.
Clownfish is the collective name for fish belonging to the Clownfish genus of the Perciformidae family. Body length is only 5-6 cm. The body is brightly colored, mainly red and orange, except for the transparent pectoral fins and soft dorsal fins, the rest of the fins are black; The body shape is odd and the body color is variable, usually with white stripes down the side of the body. It gets its name from the two or three white stripes on its body that resemble a Peking Opera clown.