Heat the olive oil in a large saucepan over medium heat. Pour onion, garlic, and celery into a saucepan, fry, stirring occasionally, until soft, about 3-4 minutes.
Add fish and squid rings to a saucepan, fry, stirring occasionally, for about 2 minutes.
Then add the broth, tomatoes, thyme, salt, and pepper, cover, and cook the seafood stew for 3-4 minutes. Place the clams in a saucepan, cover, and cook the seafood stew for about 2 minutes, until the shells open. Remove shells that have not opened from the saucepan.
Serve the seafood stew on the platter immediately.