Further ideas...
Some possible meanings for this card could be;
1) Sabotage.
Possible conection to the event where clogs (sabots) were used to jam machinery. But unless the machinery was related to the fishing industry, this isn't feasible. Additionally, there are other ideas of how the word 'sabotage' came into being.
2) Word play or pun.
After translating the words "fish", "clog/shoe" and variations into French, I'm none the wiser. I'm not french.
3) A religious significance or meaning.
"Shoes of the Fisherman" ???
4) Could this be a fish that walks?
Perhaps 'fishy' conditions or situation, or a 'fishy/slippery' person - not to be fully trusted?
I'm running out of ideas....
Bee
EDIT: Next day.... I've arrived at the most obvious meaning, and it 'feels' right for the period and type of card. Needless to say, it's not any of the above!