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Gymnorhamphichthys
, which differs from
the rest of the fishesbyhavingadifferent
pattern and a different head form. This
means that there are at least two species
of
Gymnorhamphichthys
inPeru.
Compsaraia samueli
This knife eel, a member of the family
Apteronotidae, is probably the most
bizarre of all the New-World knifefishes.
Many Apteronotidae develop distinct
sexual dimorphism, in thatwith theonset
of sexual maturity the males develop a
much-elongated snout or undergo other
changes in the head region; in addition
the males often grow larger than the
females. The
differences
are
so
considerable that they have often led to
double descriptions because male and
female were thought to be different
species. Themales of
Compsaraia samueli
develop such long jaws that one cannot
help but wonder how they manage to
feedat all!Were this fisha cultivated form
rather than a natural species, it would
undoubtedly be regarded as a case of
animal cruelty by so-called animal
protectionists. This prolongation of the
jaws is used by the males during mock
battles.Twomales faceoneanother,open
theirmouthswide,andpusheachother to
and fro with their jaws, very much like
deer during the rut. Unfortunately we
know very little else about this knifefish,
which attains a length of around 20-25
cm. One has to wonder whether the
femalesare in someway impressedby the
"luxury-model jaws" of the males. Only
extensive aquarium observations can
answer this and further questions.
Unfortunately to date only a very few
specimens of the species have reached
Europe, although it occurs in the
immediate vicinity of Iquitos and is by no
meansuncommon there.
A specimen of an identically colored
speciesof thegenus
Sternarchella
reached
Aquarium Glaser as a bycatch with the
Compsaraia samueli
. Could this be a case
of mimesis in knife eels, ie species that
mimic one another? And what could be
the purpose of such a mimesis? Again,
only aquarium observations can provide
answers to suchquestions.
Sternachella
sp
.,
bycatchwith
Compsaraia samueli
Adontosternarchusnebulosus
The genus
Adontosternarchus
also
belongs to theApteronotidae. It currently
contains five species, one of which,
A.
nebulosus
, wasn’t described until 2007.
These species are generally of moderate
size, rarely exceeding 20 cm total length.
In thisgenus themales remain somewhat
