They do look like fish as the DI also show them. This may be a help to you also.http://www.humminbird.com/Category/S...AQ/FishArches/

  • Boat Speed – with a boat running fast it is traveling across more bottom area and target information than when it is traveling slow. With the same Chart Speed setting as when the boat is moving slow, the depth sounder will have to compact any information it ‘sees’ when running fast. The depth sounder has a better opportunity to arch fish if the boat is moving at a slower speed. Also, when a boat is moving fast, small air bubbles may be getting under the transducer, decreasing the sensitivity of the depth sounder. Try slowing the boat or matching the boat speed with the Chart Speed setting.
  • Chart Speed Setting – if the Chart Speed is set too high, the depth sounder will draw an elongated arch that may not be recognizable as an arch. With the Chart Speed set at a high setting, the arch may be spread across several screens. With the Chart Speed too low, the depth sounder may be drawing the arch but it may just look like a ‘blob’ of pixels shown all together. Again, try matching the boat speed to the Chart Speed setting. During field trials we have gotten reports that the depth sounders were not showing fish as arches. Setting the Chart Speed to a lower, slower setting ‘fixed’ the reported concern.