[Ebook] 500 freshwater aquarium fish - Characoids

Although members of the family Characidae can be very different from each other (the Piranha and the Neon Tetra are examples of this), they share a sufficiently large number of similarities for most authorities to believe that they belong to the same family. However, pending a detailed review, they are grouped by some authors, including Nelson, into a number of different subfamilies.

Broadening the issue further, there are many other fish species that share some characteristics with the members of the Characidae; however, they also exhibit significant differences. Therefore they are not, strictly speaking, characids, but are definitely characidlike. These other fish species are grouped into a number of distinct families. They are the Anostomidae, Citharinidae, Ctenolucidae, Curimatidae, Erythrinidae, Gasteropelecidae, Hepsetidae, Hemiodontidae, and Lebiasinidae. Together with the Characidae, they form the order Characiformes, the so-called characiforms or characoids (as opposed to characids).

The Characiformes usually have well- developed teeth—even tiny species such as the Cardinal Tetra (Paracheirodon axelrodi) have excellent dentition—and an adipose fin (a second small, fleshy, rayless dorsal fin). In a few Characiformes, e.g. the Silver- tipped or Copper Tetra (Hasemania nana), the adipose fin is not present, but in such fish other characteristics place them firmly in one or other of the characoid families. These other characteristics include a (usually) decurved lateral line, i.e. it curves downward to a greater or lesser extent (with some exceptions), and pharyngeal (“throat”) teeth. Characoids lack barbels and the upper jaw is not usually protractile, i.e. extensible. There are also several skeletal features relating to the tail bones, fin rays, and so on, which identify fish as characoids.

Within this broad framework, ten families can be identified. Within them, there is a total of about 240 genera and 1 ,350 species, of which around 210 genera occur in Africa; the remainder are largely distributed in Central or South America, with a relatively small number in Mexico and southwestern United States.

[Ebook] 500 freshwater aquarium fish – Characoids

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