First you need to cook the marinade. Pour water into a pan, add all the spices, salt and sugar, bring to a boil and cool.
Cut the onion into half rings and transfer half to a bowl in which we will pickle the fish, squeeze the juice from one circle and put it on the onion. Transfer the peeled and gutted fish, repeat the onion layer, squeeze the juice from the lemon again and put on top.
Pour the marinade, set the oppression and pickle in the refrigerator for 1 day. Bon Appetit!!!