Bacteriophages are one of the most common microorganisms on the earth, and are potential biocontrol agents for multidrug-resistant bacteria. Aeromonas salmonicide is a major bacterial pathogen in aquaculture. It can be responsible for furunculosis, which is a ubiquitous disease in aquaculture operation and featured by high mortality and morbidity, causing significant economic loss of aquaculture. In this study, Aeromonas salmonicida MF663675.1 was used as host to isolate bacteriophage from the sewage of a seafood market in Shenzhen, China. A novel lytic phage Asfd-1 was isolated and purified by double-layer agar plate. The morphological characteristics were observed by transmission electron microscope (TEM). The plaque characteristics were observed as well. The whole genome and phylogenetic analysis of phage Asfd-1 were carried out by bioinformatics methods. The results show that plaque of the phage was round and transparent with size of about 1 mm in diameter. TEM shows that Asfd-1 has an isometric, elongated and icosahedral head of 100 nm in diameter by 71 nm in width and a 51 nm contracted tail. Comparative genomics analysis indicates that Asfd-1 has a double-stranded DNA of 168 962 bp in length, and the content ratio of guanine and cytosine is 41.53%. Asfd-1 genome encodes 263 open reading frames and 16 tRNA genes, indicating that Asfd-1 is not totally dependent on host cell transcription machinery. Combined with TEM and phylogenetic analysis, it proposes that Asfd-1 belongs a new member of the T4 virus, Myoviridae family, Caudovirales order. Based on its microbiological traits, phage Asfd-1 is a promising agent that can be used for controlling Aeromonas salmonicida infection.