Characiformes are the group of fish that contains more than a thousand different species including the most beloved fish like Piranhas or Neon Tetras. These fish can be found in the rivers and lakes in Central America, South America and even in Central Africa. Since there are more than a thousand different species in this group, we’ll be focusing more on the species that are kept by the aquarists/hobbyists around the world.

Hatchetfish

Unlike many other freshwater fish, hatchetfish likes to hangout close to the surface and thus they are considered as a top-dwelling fish. They are named after their unique body shape – which actually looks like a hatchet! There are many species for this group but the ones that are kept by the aquarists are relatively smaller in size. They can grow up to 3 inches at most and they like to school together.

• Carnegiella Marthae (Blackwing Hatchetfish)
• Carnegiella Myersi (Pygmy Hatchetfish)
• Carnegiella Schereri (Dwarf Hatchetfish)
• Carnegiella Strigata (Marbled Hatchetfish)
• Gasteropelecus Levis (Silver Hatchetfish)
• Gasteropelecus Maculatus (Spotted Hatchetfish)
• Gasteropelecus Sternicla (Common Hatchetfish)
• Thoracocharax Securis (Giant Hatchetfish)
• Thoracocharax Stellatus

Pencilfish

Just like hatchetfish, pencilfish are considered as top-dwelling fish. They have pencil-like bodies and that’s why they get the pencilfish as their common name. They are schooling fish so we suggest that you keep them in groups. Some of the species swims in a 45-degree vertical whereas most fish swims horizontally. They are originated from South America and we consider them as the relatives of the Tetras. Some of the pencil fish that are kept by the hobbyists are –

• Nannostomus Anduzei
• Nannostomus Beckfordi (Golden Pencilfish)
• Nannostomus Bifasciatus (Whiteside Pencilfish)
• Nannostomus Digrammus
• Nannostomus Eques (Hockeystick Pencilfish)
• Nannostomus Espei (Barred Pencilfish)
• Nannostomus Harrisoni
• Nannostomus Limatus (Elegant Pencilfish)
• Nannostomus Marginatus (Dwarf Pencilfish)
• Nannostomus Marilynae (Greenstripe Pencilfish)
• Nannostomus Mortenthaleri (Coral Red Pencilfish)
• Nannostomus Nitidus (Shining Pencilfish)
• Nannostomus Trifasciatus (Three-lined Pencilfish)
• Nannostomus Unifasciatus
• Pyrrhulina Rachoviana

Pacus and Piranhas

The Serrasalmidae are a family of characiform fishes and it contains more than a hundred fish species. Not all the fish are kept by the aquarists but some are: Pacus and Piranhas. These fish can get big — really big – like a foot or even two feet long. They are originated from the rivers of the South America.

• Colossoma Macropomum (Red Pacu or Tambaqui)
• Metynnis Hypsauchen (Silver Dollar)
• Myleus rubripinnis (Redhook)
• Myleus Schomburgkii (Disk Tetra or Disk Pacu or Black-ear Pacu or Black-band Myleus or Black-barred Myleus)
• Mylossoma Duriventre
• Piaractus Brachypomus (Red-bellied Pacu)
• Pygocentrus Cariba (Black-spot Piranha)
• Pygocentrus Nattereri (Red-bellied Piranha)
• Pygocentrus Piraya (Piraya Piranha or San Francisco Piranha)
• Serrasalmus Rhombeus (Red-eye Piranha)

Tetras

They are arguably the most kept fish in the aquarium hobby and our favorite group of fish! One of the smallest fish in the characiformes group.

They come-in all different sizes but they are relatively small fish with a few exceptions. They like to school that’s why we recommend that you keep them in groups (and they are small, you better have more of them so that you’ll see some action going on). Most of the species under this group can be really good fit for a community tank because they are peaceful to their own species and other fish. They can be nippy sometimes but since they are small in-size, it makes it easier for other fish to dodge them. Some of the tetras that are popular in the aquarium hobby are –

• Alestopetersius Caudalis (Yellow-tailed African Tetra)
• Aphyocharax Alburnus
• Aphyocharax Anisitsi (Bloodfin Tetra)
• Aphyocharax Dentatus
• Aphyocharax Paraguayensis
• Aphyocharax Rathbuni (Redflank Bloodfin Tetra)
• Arnoldichthys Spilopterus (Niger Tetra or African Red-eye Tetra)
• Astyanax Jordani (Blind Cave Tetra)
• Axelrodia Riesei (Ruby Tetra)
• Bathyaethiops Breuseghemi
• Bathyaethiops Caudomaculatus
• Boehlkea Fredcochui (Cochu’s Blue Tetra)
• Brachychalcinus Cf. Orbicularis (Discus Tetra)
• Brycinus Nurse
• Chalceus Macrolepidotus (Pink-tailed Chalceus)
• Copella Arnoldi (Splash Tetra or Splashing Tetra)
• Crenuchus Spilurus (Sailfin Tetra or Sailfin Characin)
• Exodon Paradoxus
• Gymnocorymbus Ternetzi (Black Tetra)
• Hasemania Nana
• Hemigrammus Bleheri (Firehead Tetra or Rummy-nose Tetra)
• Hemigrammus Erythrozonus (Glowlight Tetra)
• Hemigrammus Hyanuary (January Tetra or Green Neon Tetra)
• Hemigrammus Ocellifer
• Hyphessobrycon Amandae (Ember Tetra)
• Hyphessobrycon Anisitsi (Buenos Aires Tetra)
• Hyphessobrycon Callistus
• Hyphessobrycon Columbianus
• Hyphessobrycon Eques (Serpae Tetra)
• Hyphessobrycon Erythrostigma (Bleeding Heart Tetra)
• Hyphessobrycon Flammeus
• Hyphessobrycon Haraldschultzi
• Hyphessobrycon Herbertaxelrodi (Black Neon Tetra)
• Hyphessobrycon Heterorhabdus
• Hyphessobrycon Loretoensis
• Hyphessobrycon Pulchripinnis (Lemon Tetra)
• Hyphessobrycon Pyrrhonotus
• Hyphessobrycon Rosaceus
• Hyphessobrycon Roseus
• Hyphessobrycon Scholzei (Black Line Tetra)
• Hyphessobrycon Sweglesi
• Iguanodectes Spilurus (Green Line Lizard Tetra)
• Inpaichthys Kerri
• Ladigesia Roloffi (Jelly Bean Tetra)
• Megalamphodus Megalopterus (Black Phantom Tetra)
• Megalamphodus Sweglesi (Red Phantom Tetra)
• Moenkhausia Pittieri (Diamond Tetra)
• Moenkhausia Sanctaefilomenae (Redeye Tetra)
• Nannaethiops Unitaeniatus (Oneline Tetra or One-lined African Characin)
• Nematobrycon Lacortei (Rainbow Tetra)
• Nematobrycon Palmeri (Emperor Tetra)
• Paracheirodon Axelrodi (Cardinal Neon Tetra or Cardinal Tetra)
• Paracheirodon Innesi (Neon Tetra)
• Paracheirodon Simulans (Green Neon Tetra)
• Petitella Georgiae
• Phenacogrammus Interruptus (Congo Tetra)
• Poecilocharax Weitzmani (Black Darter Tetra)
• Prionobrama Filigera
• Pristella Maxillaris (X-ray Tetra)
• Rhoadsia Altipinna
• Thayeria Boehlkei (Penguen Tetra)
• Tucanoichthys Tucano