What are unusual fish? These are simply strange fish… rare fish, odd fish and downright weird fish!
Unusual fish are types of tropical fish that just don’t fit any of the typical groups. This a collection of the odd fish containing various true bony fish such as the Arapaima and Butterflyfish, pseudo-bony fish like the gar, pike, and sturgeonfish, as well as lungfish and a bunch of other strange fish. These specimens make fascinating aquarium inhabitants, and an impressive display of unique showpieces for top-notch aquarists.
There are many true bony fish and pseudo-bony fish families, and they are found in both freshwater and sea water. Odd fish included here are true bony fish families that often have very few species, sometimes containing only one. The pseudo-bony fish are most closely related to the true bony fishes, and are very similar, but they are much older in an evolutionary sense. Lungfish, also known as salamanderfish, are also some very primitive fish but there are very few species.
These fish are truly unique aquarium specimens. The unusual fish species list below includes familiar varieties and lesser known species of rather strange fish. Each fish guide has in-depth fish information including their places of origin, habitats and behaviors as well as the fish care needed for successfully keeping them in the aquarium. Fish pictures are also provided within each fish guide to help with fish identification and to aid in choosing pet fish.
Placed in their own sections are true bony fish and pseudo-bony fish families that contain a number of species. True bony fish types include cyprinids (barbs, danios), characins (tetras), catfish, eels, elephant snout fish, killifish, knifefish, loaches, hillstream loaches, and puffers. Pseudo-bony fish types include families like bichers and ropefish.
For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care
True Bony Fish Types
There are many true bony fish and pseudo-bony fish families, and they are found in both freshwater and sea water. Their classification has been undergoing revisions in recent years. Currently, starting with the “Bony Fish” of the Super-class Osteichthyes , the true bony fish and pseudo-bony fish are placed within it as members of the Class Actinopterygii, or “Ray-Finned Fishes”. This class is divided into two Sub-classes, Chondrostei and Neopterygii. The Sub-class Neopterygii itself contains two Infraclasses, Holostei and Teleostei. The “true bony fish” are members of the Infraclass Teleostei.
Odd fish included here are some very interesting members of the Teleostei Infraclass. These range from one of the largest of all freshwater fish, the Arapaima, to the fancy Butterfyfish, the stick-like needlefish and flatfish like the Tonguefish.
Pseudo-bony Fish Types
The pseudo-bony fish include members of families such as true gars, pikes, and sturgeonfish. These are also members of the Super-class Osteichthyes of “Bony Fish” in the Class Actinopterygii of “Ray-Finned Fishes”. But at this juncture some are members of the Sub-class Chondrostei (sturgeon), while others are also in the Sub-class Neopterygii (flounder, gar, pike). These fish are most closely related to the true bony fishes, and are very similar, but they are much older in an evolutionary sense. Pseudo-bony fishes include such as families of true gar, pike, flounder, and sturgeonfish as well as families like bichers and ropefish.
Lungfish, also known as salamanderfish, have a different classification structure. They also start with the “Bony Fish” of the Super-class Osteichthyes at the top. But they then branch into the Class Sarcopterygii of “Lobe-finned Fish” and are placed in the Subclass Dipnoi which has two Orders, Ceratodontiformes and Lepidosireniformes. The lungfish also retain some of the very primitive characteristics of the Osteichthyes, but there are only about 3 species.