Little to no fish, at least in the deep ocean. Most commercially available fish (even in the present day with deep sea bottom trawlers) is in shallow waters near coasts, or on banks or reefs like the Grand Banks off the North American coast. Columbus' ships would have been stored with biscuit or flour, dried vegetables and stockfish (which could easily have been cod caught by the Portuguese on the Banks and sold in Europe). Some sea captains took advantage of fish when they could be caught, or bought fish (and information) from fishermen inshore, but no prudent captain would rely on deep-sea fishing for his caloric needs.