This creature you will find in any type of water. Also brackish and salt water! And once in every season . You can always fish with this Gammarus.
One morning at the reservoir trout didn't take anything I was fishing with. Mid-day there was an older gentleman also a flyfisherman. He started catching one after each other... I did not understand and desperate I decided to ask the gentleman whatever he was fishing with. He replied, '' a gray amphipod , ... and a little bit fast retrieving it. Gammarus on the tippet and making 8's ..... Boom!... even at the first cast fish on the hook.