What are KILLIES?
Origin of the name Killifish.
Killifish are secondary freshwater fishes, i.e., primarily living in freshwaters today but originating from marine coastal waters in the remote past.
Their common name, Killi (plural, Killies) stems from an
old Dutch name, used by immigrants of USA in the seventeenth
century to qualify fishes living in small channels,
the "kills", that reminded them their home country.
Progressively, the name has been extended to other groups
of related fishes from northern America, Mediterranean
countries and finally tropical countries, when
aquarists of the twentieth century became passionately
interested by these fishes.
Systematics of Killifish.
Scientifically speaking, Killifish are Teleosts (vertebrate
fishes), members of the superorder Atherinomorpha, of
the order Cyprinodontiformes, with current relatives
in related orders Beloniformes (Oryzias),
Cyprinodontiformes -or shortly Cyprinodonts- are split artificially into
species, properly Killifish (770+ valid species), and viviparous groups
(about 300 valid species),
properly livebearers, featuring Guppies, Xiphos, famous
aquarium fishes, or the beautiful Goodeids, or Anableps (4 eyed-fish), or Gambusies, (unfortunately) planted all over the
world, for mosquito control.
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
- Rivulidae from Central and South America with 3 subfamilies: Rivulinae, Cynolebiinae and
- 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 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.
other fish such as Characoids or Percomorphs which inhabit fresh water and yet
show great morphological range, the egg-laying and live-bearing Cyprinodonts (gonopodium
apart!) form a remarkably homogeneous entity; alongside this morphological
homogeneity has been demonstrated an extreme heterogeneity in genotype and in
male color pattern, which can be translated into genera comprising fifty or
more species. In addition, here and there, an atypical species, often dwarf,
often relict, differs from the homogeneous norm and is given its own genus name
(or subgenus, depending on the author). There are not less than 31 monotypical
genera or subgenera today out of a total of 104 genera or subgenera deemed
valid. These important genera are today very difficult to place in the
suprageneric phylogeny of Cyprinodonts.
Biogeography, habitat, and behavior of Killifishes.
Killifishes, or oviparous Cyprinodonts, occur all
over the world, in tropical and temperate regions of
Africa, America and Eurasia, except in northern and eastern
Europe (today, but fossils are known) and in Australasia, east of the Wallace line. Then, they can be
found all over Africa (except generally in the desert of Sahara and neighbouring regions,
and of the extreme southwestern Africa), all over South America (except Patagonia
and the south-western Pacific coastal plain), all over Central America, all over
North America, including Canada (except its polar regions), all over
Mediterranean countries and the Middle East (except deserts), and from Pakistan
to Vietnam and Indonesia, up to Lombok (or New Papua if not artificially
Killifishes, or oviparous Cyprinodonts, live in reclusive waters (usually
creeks, temporary pools, overfloods, and margins of lakes and rivers), primarily in coastal lowlands, but also in
highlands, where they are quasi exclusive (photos in BIOTOPES): they are
then very different from the standard ichthyofauna that
lives in rivers, such as Cichlids, Barbs, Characids,
Killifishes, or oviparous Cyprinodonts, feature some of
the oddest fishes, such as:
- Kryptolebias marmoratus, a selfish hermaphrodite, inhabiting mangroves from
the Florida panhandle, U.S.A. to the Sao Paulo latitude in southeastern Brasil;
- Cyprinodon diabolis, restricted to a single cave in Devil's Hole, in
western desert of U.S.A., with the smallest population of a fish species (around
- annual species (more than a hundred species, in tropical Africa and America),
living in seasonal biotopes only filled with water during the rainy season and
dry otherwise, and spawning eggs that needs several weeks or months to incubate
in dry mud, i.e. without water;
- divers, which cannot be seen during spawning and bury their eggs well into the
substratum: these annual killifishes became famous as "instant fish"
in the 1950'ies when a consumer goods company offered to their customers a small
bag with eggs that became fish within a few minutes when put in water;
- schooling fishes or lampeyes, because they bear a lightning spot on eye,
members of the genera Lamprichthys, Procatopus, or Plataplochilus,
spawning in rock holes;
- intermediate species between oviparous and viviparous fishes with internal
fertilization but external development, like for Campellolebias species
or Tomeurus gracilis;
- egg-stranding, aestivating and jumping-out-of-the-water species, like most Rivulus
species, able to wander several hundred meters or spring several dozens of centimetres
to better catch the insects for food or simply look for better
- cannibalising species, that feed on their smaller congeners, like Cynolebias,
Megalebias, Moema or Paranothobranchius species;
- adaptative species to extreme conditions, such as hypersaline reefs like some Cyprinodon
or Aphanius species, as high altitude Andes lakes like Orestias
species, with a speciation similar to that encountered in the Rift African Lake
- and many other oddities that are to be discovered in a small gallery of their BEHAVIORS,
within the database for each
species and in the answers to each individual QUIZ
scattered throughout the website.
Killifishes, or oviparous Cyprinodonts, can be interesting, depending on the view point:
Killifishes, or oviparous Cyprinodonts, are among the most
beautiful freshwater aquarium fishes: look to the few photos of their BEAUTIES
are 1750 photos in the data base!) and you
will understand why they are so attractive to aquarists.
Killifishes, or oviparous Cyprinodonts, besides combine, for aquarists, the unique
qualities of being diverse in their characteristics, of needing at least 2 weeks
of incubation, and even more for annual species (exchanging eggs by post mail is easy) and of living in small
amount of waters (creating a fish room or "Killiarium", holding
several dozens of small aquariums at room temperature, is easy). And aquarists,
also nicknamed Killi-hobbyists or Killiphiles, are grouped in national ASSOCIATIONS
(listed in the website) to exchange their experiences and fishes.
Killifishes, or oviparous Cyprinodonts, are among the most
difficult fishes for ichthyological research, because most of their explosive
evolution stems from the latest period of Earth history, and biologists, behaviourists, aging specialists,
geneticists, molecularists, morphologists,
osteologists, palaeontologists combine their efforts and discoveries to ensure
scientific progress wherever they are amateurs or professionals in INSTITUTIONS
(listed in the website).
This is the whole story of Killi-Data:
to ensure community
efforts to gather knowledge on these fishes,
just as Killifishes, or oviparous Cyprinodonts,
develop community strategies to face stringent constraints and survive into their highly adverse and
Prospects on Killifishes.
doubt Killifishes are in every way very different from the standard river fishes
and opposite by major traits:
- independent micro-populations of sympatric congeners in reclusive fragile
biotopes where they are quasi-exclusive;
- explosive recent genotypes and typified color patterns, together with an
amazing basic morphological stability (only 5 basic morphotypes, 3 in Aplocheiloids, 2 in
- probable recurrent extinction episodes except in refugia, from where a brand
new expansion process started again.
combining data of palaeogeography, palaeoecology, vicariance, endemicity,
diversity, internal and external characters of extant phylogenetic lineages, it is
possible to hypothesize their centres of origin as well as plausible scenarios
of the long term history and migration patterns of Cyprinodonts, since their
birth more than 150 million years ago.
the explosive evolution of the tropical Cyprinodonts, is to be found in the near
past. Apart from the very old development of the few distinguished morphotypes
linked to major Earth events (continental drift), most of the evolution spur is hypothesized to be
recent, linked to climatic fluctuations and especially to the late glacial
maximums of the Pleistocene-Holocene. The evolution of these fishes, pushed by
similar and severe constraints, is playing with a limited number of options. The
many similarities between their characteristics in the Old and the New Worlds,
or between those of Eurasia and North America plus the Andes, change then
somewhat the picture from a purely haphazard convergence into the disclosure of
very few options, variably combined as much as possible.
Mar 26 2006 12:05:50
Copyright Huber, Killi-Data 1994-2006.