6th Jan is officially a bank holiday, to the Canarians it is the equivalent of our Christmas day.
The majority of the Canarian owned businesses will be closed but as it is a busy time you will find some places do open. The majority of the british owned businesses will be open as normal.
Large supermarkets like Mercadonna and transito will be closed but you should find some of the smaller ones open. There is a small supermarket aprox half way along the marina and they will be open as normal - I've just asked them the question.
Have a good holiday