Arrange two racks in the oven: one in the middle and one below. Preheat oven to 400°F.
Place tomatoes and green beans on a rimmed baking sheet. Drizzle with olive oil, season with salt and pepper and toss. Evenly spread keeping vegetables separate.
Thoroughly pat catfish fillets dry. Season all sides with salt and pepper. Center fillets on the baking sheet.
Place both baking sheets in the oven and cook for 10 minutes.
Grate parmesan and shred mozzarella cheese.
After 10 minutes, remove both baking sheets from oven.
Coat catfish with a thin layer of pesto until each fillet is evenly covered. Place back in oven and cook for an additional 5 minutes.
Toss green beans before sprinkling with parmesan and mozzarella cheese. Bake for 5-10 minutes or until cheese is golden brown and bubbly.
Remove both sheets from oven, plate and enjoy!