True questions and unshared
answers... Hobbyists often ask to themselves questions that already have
their good answers, but these answers are not widely dispatched or the good
answers fail to prevail because of old beliefs.
With Internet, it is both
possible to dispatch the good answers to everybody and to keep these good
answers permanently online for newcomers, while a printed article is replaced
by another and it is not always easy to access to old articles.
No headline ! The present
author is definitely not an aquarist, but he has the connection with the expert
aquarists and the credibility to discuss those true questions with objectivity
This page is written for standard
aquarists to help them separate hard data from fake data and unjustified
rumours, to help them develop the right cooperative approach that is
prevailing in Killi-Data and among true experienced hobbyists who are members of
To communicate better, questions
are provocatively set and answers are split into past (insufficient or
erroneous) answers, present (true, but not always complete) answers, and future
answers (the path to a better understanding).
PAST, PRESENT, FUTURE
changes : scientific names of fish are changing all the time with no
value added and because so called scientists keep quarrelling to end up
with a real mess?
names keep changing because there are different schools of thoughts
among scientists who are driven by egos, nationalism... the best is to
follow the expert of the country where you live.
names do change and this is normal... just a consequence of progress
in zoological science and knowledge... and
hobbyists have to live with it... any new publication on Killifish bears
a progress on our understanding about those very complicated and
difficult-to-study fishes... normally any coming publication is peer
reviewed and any controversial matter or any opinion-based-only move is
not accepted... however, scientists are different (like anybody, like
aquarists) and it is not unacceptable that disagreements arise
(improvement also derives from positive conflicts, but these
disagreements must be evidence-based, not opinion based, and
courtesy-based!)... of course,
scientists are either "splitters" (who tend to describe many
names) and "lumpers" (who tend to accept less numerous names),
just like there are more analytic people (who divide, separate) and more
synthetic people (who gather)... both attitudes are respectable and none
is the best for all cases, permanently... nonetheless, the tools today used by
researchers (e.g., sequencing genes, computerized matrixes of characters,
detailed morphology, osteology, behaviour)
push to a splitting strategy... and you cannot ask a young researcher
not to erect new names simply because there are enough : today a genus
gathers 5 to 15 species, while in the past it gathered up to 100 species,
this is unavoidable... the present situation for Killifish is not a mess
at all, far of it : different lists of names are available (Killi-Data
book and online,
KMI, KFN, DKG), but these lists are very similar (95% of the names are
identical) and they tend to harmonize progressively... of course, if you
compare names of today with names in your books or journals, published say 10-20
years ago, differences may be huge, but this is not a mirror of a mess,
but, instead, of major scientific improvements (and Killi-Data helps you by
editing a list of present names, in comparison with the 2 major recent
books by Seegers and Wildekamp, and also a list of all NAME
CHANGES since 2001, and also POCKET
KILLI-DATA, a yearly pocket guide with all valid names and aquarium
populations and on top of that Killi-Data has prepared for you a list of
correspondences of old names vs. current names, if you are a perfect aquarist, you
will make your best to use the actual full name of your fish (and again
Killi-Data helps you by editing a constantly updated list of valid names,
located in the GUEST section)... if you are a standard aquarist who is not interested by
scientific issues, you do not need to use the full actual name of your
fish, but instead you have to keep in mind the aquarium population of
your fish (to avoid risky mixing), e.g. Buenos Aires, and the species
name of your fish (that changes very rarely), e.g., nigripinnis...
if you are a pragmatic and reasonable aquarist, you may also add the old
name behind the new one, when you distribute your fish (e.g., Austrolebias nigripinnis
[Cynolebias]- Buenos Aires)... in conclusion, be sure that the
issue of quarrelling about names is definitely old-fashioned among
present researchers, who to-day simply do not care... issues of
cataloguing, of good spellings, of dates and authorships are to-day 99%
solved, but the rest -knowledge on phylogeny, on collections, on
conservation- is far more difficult and killifish have taught all
present researchers how to be, or to become, modest !
there are not more than 50 researchers on Killifish worldwide and
cooperation can be enhanced by courteously distributing manuscripts for
comments before submission to publication... Killi-Data list of valid
names aims to lead towards a full harmonization, not because of
hegemony, but because this is the best base for strengthened cooperation
between aquarists and researchers, to speak the same language... if you
are not an Internet nut, then you may, instead of registering to Killi-Data online,
obtain the current booklet "POCKET
KILLI-DATA" from your Killifish Association (most have
subscribed and do distribute it for free or against a small charge to cover
their printing costs)... to make it straight, your question is relevant and
respectable, the answer is practical and easy (2 names per species, as a
minimum : population and species names)... and forget about quarrels : name changes are not today
as frequent as in the past... just compare with names and trade
marks of your "ordinary life" : how many of those, common and
fashionable words, say 20 years ago, are now disused ?
permanent names and codes of collections : what do I do if I am not a member of a Killifish Association?
is better to forget all about this stuff that was introduced by
specialists to prevent entry for ordinary aquarists.
if you use only the species name and the aquarium population, then the
risk of any name change is extremely low (not more than 1 or 2 cases per
year over 800+ valid Killifish species) and your names will be nearly
permanent... some people add codes that are an additional information to
the population name : these codes identify the year and locality of
collection by a
combination of letters and numbers (e.g., PEG95/2: locality 2 of the
1995 collecting trip in Gabon by Guido Passaro and Wolfgang Eberl), they are
welcome and useful but
not compulsory and they can be copied with errors (e.g. PEG95/2 into
PEG98/5, a very different strain)... in terms of updating, you can trust
Killi-Data : it is continuously
updated according to science progress, based on published evidence... finally,
how many changes can you trace during the last 20 years : very few at
the species level, very many at the genus level, hence the idea of not
bothering too much with the genus name, if you are not a killifish nut.
you are a standard aquarist, just remember the stable population and
species names ("my Buenos Aires nigripinnis")... but
soon, you'll become a killifish nut and a member of a Killifish
association and you will exchange eggs and fish with other hobbyists
from all around the world... then your involvement will become more
passionate and more serious (full name, correctly labelled ; interest in
precise populations ; code of population ; focus on knowledge, ecology and conservation) and
you will consider as normal to be informed and to apply news in terms of
names for your beloved fishes... do not forget that
Killifish are extremely difficult to study and that there are very few
researchers worldwide and time and money are limited (why not contribute
by donating specimens?)... a good scientific name will be the clearest
media of communication between 2 aquarists who do not speak the same
names : we should stay as hobbyists and only use common names for our
this is possible, and permanent names can be achieved either through
common names or through codes with 3 letters, like CAM for Aphyosemion
cameronense ... simple and practical.
with 800+ valid Killifish species and more than 3000 different aquarium
populations, with international exchange of fish and eggs, it is simply
unachievable... by nature common names use national languages (do you
understand the German names based on Prachtkärpfling?) and additional
difficulties arise when species names are identical in various genera
(e.g. dedicated to persons, like Myers or Roloff, or with the same
meaning like marmoratus, or from the same country like, as above, Aphyosemion
cameronense or Lacustricola camerunensis!)... codes with 3 letters seemed a good
idea in the sixties when the number of names with aquarium strains was limited, but today it
is unpractical (it has been tried to use 4 letters instead of 3, but it
did not solve the difficulties and it was less easy to remember the
certainly, the next step is to make sure that no sale to the commercial
network (wholesalers, local shops) is undertaken without at least the
name of the aquarium population (origin) and at best without the full present
scientific name... similarly, no commercial import from native countries
of Killifish should be finalised without obtaining the precise origin of
the strain (secretive strategies by importers during the pre-world war
period has led to unbelievable misunderstandings and errors)... this is
also the reason why Killi-Data online is entirely free for petfish
magazine editors : hopefully they will then use good names and
"solid data" !
varieties : we must separate hobby from science by having few strains
that we cross to obtain upgraded varieties (better colours, extended
fins, curious morphs) like for livebearers or Kois?
this is possible, this will enhance the competition in contests, with
more fun, and this will leave the wild fish where they should stay, i.e.
is clearly not advisable : it has been well known since the sixties that
killifish hybrids are commonly sterile (notably at the second
generation), even if the 2 mixed populations originate from nearby
locations and look like each other... this stems from very different
genes that were produced during evolution (and induced by major climatic
and/or orogenic changes).
the contrary, a trend is developing among experienced hobbyists to
specialize on rare strains and even endangered species, in order to
be sure that their grand children may still look at some fantastic
beauties among Killifish that are strongly endangered by human
industrialization and/or nonsense... and the conservationist behavior
also rightly pushes to maintain aquarium strains, because unreasonable
attitudes may well result one day in the complete ban of Killifish
importation from the wild by legal authorities (not a theoretical
tanks : we should keep our Killifish with commercial fish just for
pleasure at home, why more?
no killifish can be kept in community aquariums, forget it.
most Killifish tend to be reclusive in nature (they live in shallow slow
moving or stand still waters), i.e. not mixing with the standard fish
fauna from rivers, it is an error to believe that they cannot live in community
tanks... first, Lampeyes are great in tropical community tanks (a group
of 10-20 specimens swimming against the current is magnificent) together
with Characoids or Barbs or small shy Apistogramma-like cichlids... second, most other
Killifish, except annuals, may be mixed with standard aquarium fish
(notably Epiplatys, Aplocheilus, Pachypanchax), provided
that these fish are not predators or aggressive or of a much larger
size... third, poor swimmers among killifish (notably Aphyosemion,
Rivulus) may also be mixed with not
very active fish like catfish, Pantodon... the issue of annual
Killifish is another story, but their life cycle is so specific that
rare people think of bringing them to their living room aquarium (except
for old age retirement... of the fish, not of the aquarist!).
that once you have poured a female into a community tank among other
Killifish females, it is lost for breeding purposes (females are too
much similar and misidentifications are frequent)... apart from that
caution, why don' t you try to create, instead, a community aquarium
only with Killifish that live in the same area : this will be a mirror
of reality, because in nature there are often several species, annuals
and non annuals, that live together !
sliders : how to avoid this frustrating problem?
||Past: we should stick to few strains with strong selection of the
best individuals, like in nature, in order to avoid the problem that
just correspond to degenerated material.
sliders for annuals is a problem of the past and too few aquarists are aware of this
: just drop an effervescent tablet of oxygen in
your fry aquarium when the problem arise, and that's it (a not 100% miracle, though).
Future: this excellent
trick, discovered by fellow aquarists
from Killifish Associations (e.g. Jorge San Juan of Spain), will not prevent you from patiently
gathering your own observations, i.e. those conditions who naturally
prevent belly sliding (and from reporting your experience to Killi-Data)...
by the way, the problem is not reported in nature, simply because belly
sliders would be an ideal prey ! Finally if the problem is not 100%
solved, why not experiment new solutions that you imagine ?
sex ratios : how to solve that triggering problem?
your water chemistry and temperature, and you'll get some success, who
Present: for extremely unbalanced
is easy to prevent that issue by putting 5 to 10 fry in a small
(isolated) aquarium (instead of all the progeny in a single large tank) : this will
end up in a ratio of 50/50, or 40/60, or sometimes even 30/70... if this
is not enough, proceed to the extreme option of putting only 2 fry per
(isolated) aquarium and you'll have a perfect pair in each (mind you, this is not
sorcery : sex reversals are routine processes in nature and Killifish
-and livebearers- are not a special case, if sex is genetically
pre-arranged, which has to be demonstrated!).
Future: this excellent
trick, discovered by fellow aquarists
from Killifish Associations (e.g. Jim Robinson of Canada), will not prevent you from patiently
your own observations in terms of best practices for chemical data and
temperature of water (and from reporting your experience to
Killi-Data)... and it is not 100% efficient ! Finally if the problem is
not 100% solved, why not experiment new solutions that you imagine ?
aquarium conditions : what are the ideal conditions for each given
not bother, apart from few species, all Killifish can thrive into a 2
litre aquarium (half a gallon) with acid water, from birth to death, full stop.
you were killifish, you would hardly enjoy your entire life in 2 litres
of water... clearly separate your processes into 2 kinds : operational
(to produce a good and stable aquarium strain with efficiency) and
idealistic (to have active, showy fish, in an ecological environment)...
within Killi-Data data base, the ideal ecological conditions are given
for each species : large-based aquariums with shallow water (oxygen
exchange), correct (varying) temperature, physico-chemical data of the
natural habitat, etc... apart from rare brackish or marine or
hypersaline species, killifish generally live in 2 types of conditions :
(1) pure rain water (with a lot of
humic contents -black water- or without -white water-), then slightly
acid, on sand and (2) pure rain water on silt-clay substrate, then neutral
to slightly alkaline (most
savannah annuals), a "waterproof" substrate to maintain as long as possible the availability of the water
in the pool... pH is then very rarely below 6 or above 7.5, except if
the biotope is polluted by men or women themselves !
to fellow expert aquarists... they all stress the importance of regular
changes of water (say, 30% weekly), no matter of the chemical data of
the water, provided that they are not extreme... imagine you are your
favorite killifish, would you like rotten smelly waters as a permanent
environment? ... and do not be rigid (or
sentimental), reclusive biotopes of your killies do suffer huge
variations on a year basis and fish are used to cope with them... if you
claim you are lazy, then forget about Killifish (in case it is true)... if
it is only a claim, then choose larger tanks and add a population of
Ostracods (a good food for Killifish) because these Crustaceans help
cleaning poor waters.
incubation time : for annuals, what is the 100% successful incubation
time and conditions?
best incubation time is given by the time during which the pool is
usually dry in nature and the peat condition must be like
scientific data (Bellemans, Costa, Huber) show that, within a single pond, sympatric species do
not have the same incubation pattern (notably, some species are delayed,
but then they grow quicker, and finally they "immorally" eat their
-smaller- (and more beautiful) congeners! ... and that eggs are
spawned on different strates of the niche to allow variation in
incubation conditions and in birth rates (intelligent and flexible
nature!)... please, do the same : be pragmatic and flexible... it is easy to divide the spawn into several samples
with different values in variables of moist, temperature and vacuum
(from a standard basis derived from field data of the concerned species,
published in the book Killi-Data and also in the Data Base of this
and you'll soon know what is your own best estimate fitting with your room
your own learning curve and do not behave like a rigid
"accountant" (sorry, nothing against accountants) who wants to
have the exact data and cannot imagine he may fail while strictly
complying with the "good" data... after all, if there is so
much variation reported in aquarium literature, this is not because one
author, all the more he is famous, is right and all the other authors
are wrong, but because Killifish are flexible (they have to, if they
want to survive the constraints of their reclusive biotopes... not only
the mediated tsunami or El Niño, but the more species-threatening
glacial periods, the last one being only 2500 years old and having
lasted many many decades!... or simply the yearly floods which routinely
disrupt everything in the Killifish biotope : water chemistry being the
cooperation : why do I need to cooperate with others ?
all these idealistic dreams... you'll soon see that you'll only become
interesting when you have a rare species or wild stock.
is a wrong game... you'll soon see what cooperation means when you are
left with a single male (or female) of your favorite species...
cooperation means strength, shared experience and data, and
cannot imagine what is the most important aspect of killifish hobby for
experienced breeders... this is friendship... within the local club,
within their Killifish association, within a trans-national specialised
group, within Killi-Data community, with a foreigner with whom fish or eggs were exchanged, within a
conservationist group to achieve the maintenance of an endangered
species or population (what a reward!), with a researcher to whom
material for study was donated and who brings unheard results about
these unbelievably unique fishes !