Do fish swim with the current or against?

It depends on the species of fish. Some fish swim with the current, called downstream, while others swim against the current, called upstream. Some species of fish are able to swim in both directions, depending on the conditions. Generally, fish that are adapted to live in fast-flowing rivers or streams swim upstream, while those that live in slower-moving waters or oceans swim downstream. Additionally, some fish, like salmon, are born in freshwater and migrate to the ocean to live but return to their birthplace to breed.