Amphipoda isopoda commonly known as scuds are found swimming and crawling in pools and flats.
An important participant in behavioral drift these active, agile swimmers dart around bottom for food never in water over three feet.They feed most actively at night and on overcast days. The best hours to fish with them are dusk thru dawn.
Fish your DONS SCUD dead drift or with a twitching retrieve. 
During daylight hours trout will root scuds out of weed beds.
Amphipoda are an important to ingredient in a trouts winter diet.