I am cooking a three coarse meal and my main dish is a garlicky seared tilapia can I have suggestion for a appetizer that would nicely compliment the

Gazpacho If you have access to great tomatoes. Though salmon and cucumbers as suggested is hard to beat.

Given the season, a classic tomato with mozzarella and basil can't be beat if you can get freshly picked heirloom tomatoes. I also like to do sliced english cucumber rounds topped with smoked salmon, a smidgen of creme fraiche, and a sprig of dill. It takes minutes to prepare but is an elegant finger food that people love.

cold options might be a watermelon salad / fattoush / tossed green salad with a bright citrusy dressing. hot options could be a pizza or galette with fresh tomatoes or how about a nice simple pasta with fresh tomato and zucchini? Are you serving the fish with any sides?