No. 57: May-Jun 1988
Credit cards and bank cards are commonly kept in holders made from eelskin. So what! Who likes eels anyway? Well, there may be more to eelskin than meets the eye. Thousands of bank cards, when taken out of their eelskin holders, have failed to work in bank machines. The electronic coding on the cards has somehow been erased or scrambled. Perhaps, says one theory, the eelskins have bits of magnetite in their skins for navigational purposes. (Some other animals have such magnetic particles in their bodies to help orient them.) But could these tiny particles be powerful enough to erase card information? Another theory is that magnetic clamps on purses and handbags are the culprits.
(Anonymous; "Credit Cards Fall Prey to Primitive Fish," New Scientist, p. 30, March 3, 1988.)