amphipods eating clam ?

[TimT]

FME peppermints wont bother clams.

I would suspect there are lots of different species of amphipods, each with their own dietary preferences. Animals tend to prefer the easiest sources of food. Perhaps feeding meaty foods would distract the pods from the clams by providing an easier source of food. Then if you added a pod predator to reduce their population density during the day it might solve the problem.

You said that the problem started after you lost the copperband so it must have been keeping the pod population in check during the day.

If you don't want to go the wrasse method you could always try an Orchid Dottyback, Mandarin Goby, Rainford's or Hectors Goby etc.