To create a harmonious and cohesive kitchen design, consider adding natural elements that complement your built-in indoor aquatic plant garden. Incorporate materials such as wood, stone, or bamboo to create a sense of organic beauty. You can use these materials for countertops, flooring, or even as decorative accents. Natural textures and earthy tones will enhance the overall aesthetic and create a seamless connection between the kitchen and the garden. Additionally, consider adding potted plants or fresh herbs on the kitchen countertops to further bring nature indoors and create a cohesive design theme.