A gorgeous aquarium-strain of Blue Ghost Angelfish, Pterophyllum scalare, can make a captivating, if sometimes somewhat pricier centerpiece. However, Angelfish like this require larger aquariums (a 20 gallon high is generally recommended for a single pair) and can become aggressive with age, particularly when breeding. For these reasons, you wouldn't make this your first fish, but you could plan your aquarium around a centerpiece like this. Image credit: Matt Pedersen