Proper lighting is essential to showcase the beauty of your built-in indoor aquatic plant garden. Consider installing a combination of natural and artificial lighting to create the perfect ambiance. Natural light can be maximized by placing the garden near a window or skylight, allowing the plants to receive adequate sunlight. Additionally, you can incorporate LED lights or underwater spotlights to highlight specific areas of the garden, such as the floating lily pads or the koi fish. The right lighting not only enhances the visual appeal but also promotes the growth and health of the aquatic plants, ensuring a thriving and vibrant garden.