Rinse fish bones and heads; remove gills.
In a large stockpot, combine fish bones and heads with tomato juice through crabs. Bring to a boil; reduce heat and simmer for 1 hour or until stock is reduced by one-third. Strain mixture. Discard fish bones and heads, reserving stock and crab claws.
Cut catfish fillets into 1-inch cubes.
Combine reserved stock, catfish, and hearts of palm through sea rocket in a large Dutch oven. Bring to a boil; reduce heat and simmer for 5 minutes. Add clams and cook 5 minutes or until clams open. Top with crab claws, samphire, and sea rocket.
Note: Four bay leaves may be substituted for 14 wax-myrtle leaves. One large leek maybe substituted for one large cattail stalk. Spinach or arugula may be substituted for sea rocket.