Taxonomy is the practice and science of classification. The word comes from the Greek taxis = 'order' + 'law' or 'science'. Taxonomies, or taxonomic schemes, are composed of taxonomic units known as taxa (singular taxon), or kinds of living things that are arranged frequently in a herarchial structure, typically related by subtype-supertype relationships, also called parent-child relationships. In such a subtype-supertype relationship the subtype kind of living thing has by definition the same constraints as the supertype kind of living thing plus one or more additional constraints. For example, a fish is a subtype of the vertebrates. So any fish is also a vertebrate, but not every vertebrate is a fish. So, a thing needs to satisfy more constraints to be a fish than to be a vertebrate.

Mathematically, a hierarchical taxonomy is a tree structure of classifications for a given set of objects. At the top of this structure is a single classification, the root node, that applies to all objects. Nodes below this root are more specific classifications that apply to subsets of the total set of classified objects. So for instance, in common schemes of scientific classification of organisms, the root is called "Organism" followed by nodes for the taxonomic ranks.

Source: Wikipedia Dec. 2007

CURRENT PYRAMIDAL LIST OF 
FAMILY-GROUP NAMES 
WITH INCLUDED GENERA

Source: Killi Data Online. J.H. Huber. Dec. 2007.

This list of all Killifish family-group names and their included generic names is the most accurate available list, according to current research.

Synthesis:

Killifish, the common name for oviparous cyprinodontiformes fishes, are currently classified into 10 families (Huber, 2005): - Aplocheilidae, only from India and Madagascar; - Nothobranchiidae from Africa but Madagascar with 2 subfamilies: Nothobranchiinae and Epiplateinae;
- Rivulidae from Central and South America with 3 subfamilies: Rivulinae, Cynolebiinae and Kryptolebiinae;
- Fundulidae; - Profundulidae, monotypic (which may be included also in Fundulidae as a subfamily or in Goodeidae as a subfamily, depending on authors); - Goodeidae, with 2 subfamilies: Empetrichthyinae, oviparous and Goodeinae, viviparous;
- Valenciidae, also monotypic (which may be included also in Fundulidae or Cyprinodontidae, as a subfamily, depending on authors); - Cyprinodontidae, with 2 subfamilies: Cubanichthyinae and Cyprinodontinae (with the latter in 3 tribes, Aphaniini, Cyprinodontini and Orestiadini); - Anablepsidae, with 3 subfamilies: Anablepsinae, viviparous, the monotypic Oxyzygonectinae, oviparous, and Jenynsiinae, viviparous;
- Poeciliidae, with 2 subfamilies: Poeciliinae viviparous (except the monotypic subtribe Tomeurina -or tribe as Tomeurini, depending on authors-, oviparous) and Aplocheilichthyinae oviparous (in 3 tribes, Aplocheilichthyini and Procatopodini in the Old World and the monotypic Fluviphylacini in the New World).

These 10 families are also accepted in international data bases on all fishes, such as Eschmeyer's Catalog and Fishbase, to ensure coherence and universality. The lower levels depend more on authors : a consensus view is selected herein.

In red color.. the groups of Killi's this site is build on.