What adaptations does a fish need to swim against a current in a stream?

Answer 1

Basically the same way you walk uphill: by working a little harder.

Answer:

Fish are skilled at swimming (go figure!) and have developed a number of tricks to get upstream in rapid currents.

• The first is quite simple - strategy. The flow in a stream is not consistent. Deep pools are slow, near the shore is slower than the center of the flow, behind rocks are often quiet spots. The fish knows all of these advantageous locations.
• The second is speed. A fish can move quite quickly in water, especially in short bursts. Salmon are often seen bursting out of the water to leap up small waterfalls. For some currents this is enough to move forward for considerable periods before taking a rest. For really swift flows the "strategy" part works in. A fish swims as rapidly as it can from slow moving area to slow moving area. At each rest stop it regains energy to move forward. This same trick lets sailing boats work upstream close to shore in the slow moving currents.
• The third is cooperation. Fish often swim in schools. The front fish do most of the work of overcoming water friction, the other fish can rest and gain energy. The front fish and other fish interchange so that fresh fish can take over the lead as the front fish tire. As a result the schools overall speed increases.

Answer 2

Yes , Salmon .