Dear John,
 
Even after a year in a freezer, I am sure that your Gobiesox will be
identifiable if you decide to preserve them in alcohol or formalin. The
biggest problem with freezing specimens is some form of freezer-burn,
but this is much less a problem in a -70oC freezer than in a
conventional -20oC freezer. Usually the places where you see damage is
in the fins; they may be brittle and crack. As I am sure that you
realize, Gobiesox meandricus is not like a coelocanth or something -
rare and difficult to collect. I have done what you have described with
cottids with little ill effects, except for the fin problems. Good luck,
Steve