Possible Clues:

• One in a tight squeeze
• This fish, blue when cooked, could be undesirable
• Fish sometimes used to make dashi
• A diner's stewed fish
• Item in a tight tin
• Herring's kin
• Sarnie on the hoof packed with last of tinned fish
• Fish name derived from an Italian island
• Small oily fish
• Salad and radicchio for starters, then eat fish