Heat the olive oil in a saucepan over medium heat. Add the fennel slices and cook until caramelized on each side, about 8 minutes. Add the garlic, stir for about 30 seconds. Add the white ale, scraping to deglaze the pot.
Add the crushed tomatoes, red peppers, paprika, basil. tarragon and salt, bring to a low simmer.
Add the cod fillets, pushing gently to submerge.
Simmer until cod is cooked through and flakes easily with a fork, about 8 minutes (Note: do not boil or fish will become tough, keep tomato sauce at a low simmer).
Using a slotted spoon, remove cod from the pot, add to a serving platter.
Bring the tomato mixture to a strong simmer and cook, stirring occasionally, until thickened and reduced about 10 minutes.
Plate the cod, top with tomato mixture.