Keys Marine Direct has hand-picked cardinal fish for sale, shipped direct to your door. Cardinalfish are small, colorful marine fish known for their vibrant appearance and peaceful demeanor. They often display vivid hues of red, orange, blue, and green. These fish are well-suited for aquariums, particularly in pairs or small groups, as they can exhibit territorial behavior. Many cardinalfish species are nocturnal, becoming more active during the night. Their compatibility with various tank mates and striking colors make them popular choices among aquarium enthusiasts.