Annealing control primer(ACP)system was applied to find candidate genes related to muscle growth of Nile tilapia by screening differentially expressed genes in the muscle tissues of male and female fish.This study randomly selected five male and five female fish from Nile tilapia populations cultured under the same conditions to build a RNA pool,and differentially expressed genes of two groups were analyzed by annealing control primer system.Eight differentially expressed genes were identified and sequenced by amplification with 20 arbitrary primers.In these genes,five were already known as variant 3(LOC100691543),60S ribosomal protein L3(RL3),Parvalbumin beta-like,muscle-type creatine kinase M2-CK and transcription factor Sox4 gene,and others,while three were unknown.Base on quantitative real-time PCR,the relative expression levels of transcription variant 3(LOC100691543) and ACP6-Y in the muscle of male Nile tilapia were significantly higher than those in female fish(P<0.01),while the relative expression levels of ACP3-X,60S ribosomal protein L3(RL3),Parvalbumin beta-like,ACP15-X,muscle-type creatine kinase M2-CK and transcription factor Sox4 in the muscle of female Nile tilapia were significantly higher than those in male fish(P<0.01).All the 8 ESTs were screened by annealing control primer system,which may have participated in regulating muscle growth of male and female Nile tilapia.This study laid a foundation for further screening of muscle growth related genes.