Every now and then, we find a new fish or invert that jumps its way to the top of our wish lists. My new favorites? The Roundheads aka Longfins, Marine Bettas, Prettyfins, Comets, Devilfish, Spiny Basslets - fish from the family Plesiopsidae.
There are a few genera in this family that you may see in fish stores and aquariums. The most well-known (although still far from common) are the Assessors – the Yellow Devilfish (Assessor flavissimus) and the Blue Devilfish (Assessor macneilli). Wild-caught Assessors are still few and far between, but tankraised fish are slowly starting to become more common. Longfins, genus Plesiops are also becoming more common. The three you’re most likely to see are the Crimsontip Longfin (Plesiops coeruleolineatus), Northern Devilfish (Plesiops corallicola) and the Sharp-nosed Longfin (Plesiops oxycephalus). A few other fish from the Plesiopsidae family show up every now and then as well, like the Power’s Roundhead Grouper (Paraplesiops poweri) and the more well-known Marine Betta or Comet (Calloplesiops altivelis).
In general, fish of this family are rock-dwellers. You are far more likely to find them under a rocky overhang or perching in a cave than in the open water and some fish like the Assessors even hang out upside-down most of the time. Longfins have long pectoral fins that they perch on like legs while they survey their surroundings. These fish are ambush predators, meaning they wait for their food to come to them before striking prey with lightning speed. They are generally peaceful towards fish and inverts too large for them to eat. Their coloration is usually subdued; most are dusky or dark colored with a few, subtle, colorful embellishments. They tend to be compared to freshwater cichlids quite often in respect to their relatively lackluster appearance, but they have more character than most of the other flashy saltwater staples that everyone is already familiar with. The size range of these fish ranges as well, from the small Assessors to the moderately-sized Marine Bettas and Roundhead Groupers.
These fish are certainly in the “underrated and underappreciated” category. They are compatible with most tankmates and in even smaller aquariums and are relatively undemanding. Definitely worth a second look if you are looking for something new and unusual!