Freshwater fish.

According to the search on Baidu Encyclopedia, snakehead is a benthic fish of the genus Snakehead of the order Perciformes and family Snakehead. Also known as black fish and mullet. Mullet is a benthic fish that usually inhabits still water or micro-flowing water with thick aquatic plants and soft bottom mud. It is found in lakes, rivers, reservoirs, ponds and other waters. It often dives to the bottom of the water and maintains its balance by swinging its pectoral fins. This shows that it is a freshwater fish.