This bowl relates closely and is probably from the same atelier as one in the Cairo Museum of Islamic Art, which was found on the Fatimid site of Bahnasa on the Nile. The vertical masts here are replaced on the other by a diagonal lattice of rigging and a number of smaller fish are substituted for the large example here. Both are of the same shape which can be traced back to the lustre wares of Samarra. The Cairo example has now been firmly attributed to Egypt, and certainly the shape of the foot here, together with the slightly raised central boss and, most convincingly, the sketchiness of the drawing of the exterior support this attribution.
In an unpublished lecture, Oliver Watson demonstrated the continuity of materials used for the body between Samarra lustre pottery and Fatimid lustre. While only based on a small sample, the results indicated a continuous development, possibly with a number of the potters moving from Samarra to the more ostentatious Fatimid court. This dish would thus appear to an early example of Fatimid lustre, already showing a greater delight in pictorial representation with a wider range of subjects.

Watson, O.: 'From Clay to Frit, the Fatimid Potter's Body', lecture at Symposium on Fatimid History and Art given at S.O.A.S., London 23rd June 1986
Wiet, G.: Album du Musée Arabe du Caire, Cairo 1930, p.61