Blennies are mostly small, marine fish. Depending on the species of blenny, it may prefer tropical to cold water temperatures. Blennioid is the scientific name for what most refer to simply as the blenny. Blennioid are usually small fish with elongated bodies with large features (eyes and mouth). They are almost eel-like in appearance. Their tail fin is rounded. Since there are many different species found within the blennioid family, these fish can be seen in many different colors. But that makes it so hard to generalize about this family. Blennies are usually calm, bottom dwelling fish. Keeping of one species of blenny is usually the recommendation per aquarium. A large aquarium with plenty of hiding places rocks is also recommended for this fish as they love to hide. Several inches of substrate are a good idea as this fish can be a burrower. All species of the blennioid family shares a long dorsal fin and pelvic fins placed near the throat. Like many blennioid species, the sailfin blenny feeds on the microalgae growing in the aquarium. Blennies can be described as being detritivores. Detritivores will consume dead plant and animal matter. Some species of blennies are herbivores, though some are carnivorous. You get to choose the right blenny for your aquarium.