I installed my fishfinder a few weeks ago and it seems to be working fine. The problem I feel is when the ff goes over thermalcline areas. The depth reading starts going erratic and begins to mark dozens of fish. Is this normal? It always happen in the same parts of the lake/pond so I'm guessing something is going on below.

Assuming those are fish below me, they seem impossible to catch--cranks/hard jerks/carolina rigs and ect.

If you have on automatic set to manual and adjust depth and gain.

I've had strange things happen on auto in shallower area with a soft bottom.

is it set to show archs or little fish?

is it set to show archs or little fish?

Little fish

With the fish symbols turned on the unit easily confuses other things as fish.  Turn the symbols off.