You're in for a hard time. Fisher is not a canon concept - and neither is fish. The word closest semantically is ah for 'hunter'.

Non-canon has an answer, if you will tolerate it: ikind. This word won't be known outside thuum.org.

The above only applies if the literal meaning is needed. For metaphors, ah, yahiik 'seeker', or horvutiik 'trapper' can be substituted.