It is a small shark similar to the spurfish that is distributed throughout the Mediterranean and the Eastern Atlantic, from the Faroe Islands to the south of Senegal, including the archipelagos of Madeira and the Canary Islands.

It is a kind of depth that can be fished by dragging the bottom or using hooks, between 200 and 500 meters or more.

The fish is usually opened, dipped in a little salt and dried in the sun for 4 or more days (depending on radiation). It is then stored for a few months until consumption. Dry skin was formerly used for sandpaper.

Before being consumed, it must be soaked for about 1 day.

This fish has little commercial value but, as it can be preserved by drying for later consumption, the poorest people in Olhão began to use it for times of scarcity, usually in winter, and especially on Christmas Eve, replacing cod.

Currently, it is a delicacy more expensive than cod (around 60€/Kg), served to stew (lithão à moda de Olhão) or to accompany white beans (feijoada de litão).

This delicacy is, even today, the main dish of the Christmas Eve of many families in Olhão.

Reference:
https://algarveimaterial.wordpress.com/litao-2-2/