Pat fillets thoroughly dry with paper towels — moisture steams the fish instead of baking it. If starting from frozen, rinse under cold water to remove ice crystals, then pat dry. Season both sides with salt and pepper at minimum; garlic powder, paprika, oregano, or Cajun seasoning also work well. Mix any butter or oil sauce separately before adding. Arrange in a single layer in a greased baking dish or rimmed sheet — no overlapping. Optionally lay thin lemon slices on top.

Preheat oven to 400°F fully before adding the fish. Place the baking dish on the center rack, uncovered — covering traps steam and softens texture. Bake 10–15 minutes depending on fillet thickness. Thin fillets are often done near 10 minutes; thick cuts may need the full 15. If cooking from frozen, start checking after 10 minutes. Do not flip — tilapia is delicate and the circulating oven heat cooks it through. Target internal temp is 140°F–145°F at the thickest part. Visual and tactile cues work well for thin fillets.

Tilapia is done when flesh turns fully opaque white and flakes easily with a fork. Test by inserting fork tines at an angle into the thickest part and twisting gently — clean separation means it's ready. If it resists or looks glassy in the center, return to the oven for 1 to 2 minutes and check again. Pull fillets when they look just slightly underdone — residual pan heat keeps cooking them. Overcooking makes tilapia tough and dry. Rest in the pan for 1 to 2 minutes, then lift with a slotted spatula onto a serving plate, leaving excess liquid behind. Drizzle pan sauce over the top if desired. Serve with lemon wedges. Pairs well with roasted vegetables, rice, or a green salad.