Skeletal muscle is the main composition to body weight in fish,which provides an important indicator for somatic growth.To fully understand skeletal muscle development of mandarin fish (Siniperca chuatsi) at the early stage,paraffin sections of the first dorsal myomere of skeletal muscle at 1-41 days after hatching were carried out; fiber numbers and total fibre area were measured to describe hyperplastic and hypertrophic growth of skeletal muscle.The results showed that skeletal muscle growth of mandarin fish included increasing of both fibre numbers (hyperplasia) and fibre area (hypertrophy) at the early development stage,the total fiber numbers in the right first dorsal myomere increased from 40 to 520,and the total fiber area increased from 805.30 μm² to 186 422.77 μm². During the 1-9 days after hatching,the relative increased fiber numbers decreased and the relative increased fibre area raised slowly,the contribution rate of hyperplastic growth dropped dramatically from 60.53% to 8.80%,as opposite to hypertrophic growth.At the period of 9-15 days after hatching,the relative increased fiber numbers raised and relative increased area was on a steady phase,the contribution rate of hyperplastic growth increased from 8.80% to 20.26%,while hypertrophic growth contribution ratio decreased slightly.At the 15-41 days after hatching,both the relative increased fiber numbers and area were on the rise,the contribution rate of hyperplastic growth decreased to a steady phase and hypertrophic growth (from 79.76% to 87.41%) gradually became the dominant contributor of skeletal muscle growth.