Carp postcard from Japan

I must  confess that this postcard has puzzled me to some extent.  I can see a carp at the bottom of the card and I understand that in Japan, the carp symbolises a lot of good things among them longevity, fortune, etc.   So what is this card about?  A general “Good Luck” card?  Maybe someone with more information (or someone from Japan) would be able to shed some light on this card.