What anatomical trait protects synodontis re: electricity?

[knifegill]

I've read (reliably? I forget!) that synodontis catfish are a good cohab for electric catfish. Something to do with an extra dermal layer. So do any other fish possess that same layer of tissue which might make them candidates for cohab with an Ecat?

[Stackdeck]

I recall reading this too , never tried it though.

[Birger]

Something to do with an extra dermal layer

There is not some kind of extra "layer" of skin or tissue.

It is more the distaste experienced when trying to swallow a live Synodontis(not something I would want to try) produced throught the combination of locking spines and in some a toxin produced and forced into the wound as a spine punctures.

There is a decent understandable explanation in this paper:
Wright, JJ (2010) Conservative coevolution of Müllerian mimicry in a group of Rift Lake catfish. Evolution doi:10.1111/j.1558-5646.2010.01149.

Synos are tough but I would think even they would not enjoy being subjected to a shock from an electric catfish whether it trys to eat the syno or is being protective of itself.

Birger