From what I recall, Pisces Gourmet is a fish store, not a restaurant. I think that they may do some catering, but they do not have a space for patrons who wish to dine on fish.
They are definitely known as one of the best (if not the best) places to buy fish. Although the area that they are in known not only as Gourmet Row, but also as "the five thieves" area. A slight dig at the cost of the goods sold at the gourmet specialty shops along that part of Yonge st.