Tilapia () is one of the most important fishery species in the world and has been introduced and cultured widespreadly because of its fast growth rate, strong reproductive capacity, good adaptability and omnivorous feeding habit. However, disease has become the biggest threat for tilapia breeding. Recently, the epidemic and outbreak of tilapia disease caused substantial economic losses to aquaculture industry. Breeding resistant variety in tilapia was unimportant way to solve the problem of disease. The molecular marker assisted selection (MAS) has become an efficient breeding method for selecting and breeding tilapia, and will accelerate genetic improvement and increase selection intensity for disease resistance. The single nucleotide polymorphism (SNP) markers are used in many genetic and breeding studies because they are abundant in genomes, and can be genotyped easily. Ikaros is a kind of transcription factor with zinc finger structure that is essential to the development of lymphocyte and to the maintenance of normal immune function. Therefore, to obtain large amount of effective SNP molecular genetic markers and to perform MAS for disease resistance in tilapia, it is essential to study immune related candidate and to examine whether the SNPs in the gene are associated with disease resistance. In this study, the 5' regulatory region sequence of , length of 4178 bp, were obtained through Genome Walking method from . Bioinformatics software was used to analyze the 5' regulatory region sequence of gene. The predicted transcriptional start site (TSS) was in the initiation codon (ATG) upstream of 931 bp, and the core promoter regions was located at -57 bp to 48 bp when the TSS was specified as 1. The predicted promoter regions of gene included basic start of substructure components:TATA box, CCAAT box and octamer. The analysis of transcription factor binding sites (TFBS) showed that abundant of TFBS were located at -2200 bp to 1200 bp in 5' regulatory region of gene, such as GATA-1, Homeobox, CDP CR3+HD and AP-1. The analysis of CpG islands showed that two CpG islands were in 5' regulatory region sequence of gene, one of which was located in promoter regions and the other of which was located in the first exon. Five SNPs in the 5' regulatory region of gene were detected by direct sequencing method from the parents (P₀), which are named SNP1 (g.562, G>A), SNP2(g.217, G>T), SNP3(g.-53, C>T), SNP4(g.-220, T>C) and SNP5(g.-579, T>C). The five SNPs were sited in various regulatory elements in promoter regions which could have major implications for exact expression of gene. Based on Snapshot method analysis, the frequencies of alleles and genotypes were calculated in susceptible groups and resistant groups of ). The polymorphisms and genetic parameter of the SNPs in resistant groups and susceptible groups were calculated by software Popgen 32 and PIC. The result showed that the polymorphism information content (PIC) of the 5' regulatory region of SNPs was 0.0872~0.3747, suggesting that all the SNPs had moderate of intermediate polymorphism. The correlation between SNPs and resistance to was analyzed by software SPSS 17.0, the results showed that four of them (SNP2, SNP3, SNP4and SNP5) were significantly associated with the resistance to <0.05). Moreover, All of the SNPs in the 5' regulatory region of could formed one haplotype block and five haplotypes from the prediction of linkage disequilibrium analysis used software Haploview 4.2. The haplotypes (GGCTT) were significantly associated with the resistance to <0.05), and two of the haplotypes (GGTCT and GTCCC) were significantly associated with <0.05). Furthermore, the SNP2 and SNP5 were completely linked with each other ('=1), which could be selected as tag SNP for research of genetic breeding in . The results suggest that the four SNPs (SNP2, SNP3, SNP4 and SNP5) and the haplotypes (GGCTT) in the 5' regulatory region of could be potential genetic markers for future molecular selection of .