Crispy Tilapia Fillets with Fennel Mint Tzatziki

Name: Crispy Tilapia Fillets with Fennel-Mint Tzatziki
Ingredients: 1 cup finely diced fennel bulb plus 1 tablespoon chopped fennel fronds; 3/4 cup whole-milk greek-style yogurt; 1 1/2 tablespoons chopped fresh mint; 1 teaspoon white balsamic vinegar; 4 tablespoons extra-virgin olive oil, divided; 4 large tilapia fillets; 1 teaspoon fennel seeds, finely ground; 1 large egg white, beaten until frothy; 2 cups (about) panko (japanese breadcrumbs) or fresh breadcrumbs