Clean carrots thoroughly, and slice. Peel onions and slice. Boil water in medium-size saucepan, add onion and carrot slices, salt and pepper. Boil for 5 minutes, reduce to medium heat. Add 3 tyoes of fish, continue to cook for 20 minutes. Remove fish to cool. Fillet the cod and hake. Cut into medium squares (1/2-inch), or flake. Cube cucumbers (1/4-inch). Mix with fish and capers.
Serve as first course, with white wine, champagne or vin rose.