Preheat the oven to 425 degress and line a sheet pan with foil.
Season the fish with the fish rub, salt, pepper, and 1 tablespoon of chili powder.
Add the veggies to a large bowl. Drizzle with juice from 1/2 of the fresh lime. Season the veggies with the remaining chili powder, salt and pepper.
Add the tilapia and potatoes to the sheet pan. Cover with foil. Bake for 15 minutes.
Remove the pan from the oven and remove the foil. Add the squash and red peppers. Bake for an additional 8-10 minutes uncovered until the potatoes are soft and crisp.
Add the peeled avocado to a small bowl. Spread the remaining lime juice throughout. Mash the avocado in a small bowl. Add the crema and stir.