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Abramiteshypselonotus
The Marbled Headstander is enormously
widespread in South America and grows
to around 15 cm long. It is a true
headstander, the fishes almost always
swim with their heads pointing
downwards. The Marbled Headstander
isn’t that unusual in the wholesale trade.
But despite its attractive coloration this
fish isn’t verypopular amongaquarists,as
it is quarrelsome and likes to eat plants.
TheMarbledHeadstanders thatAquarium
Glaser recently imported from Venezuela
are, however, noticeable for their
particularly contrasting coloration, giving
rise to the suspicion that theymight be a
different species. But a glance at the
literature reveals that at present there is
only one other species regarded as valid,
namelyAbramites eques, and this species
exhibits a different color pattern. So in all
probability the imported specimens are
no more than a particularly attractive
color variant of
Abramiteshypselonotus
.
Pseudanos trimaculatusandP. gracilis
Since October 2012 AquariumGlaser has
received several consignments from Peru
containing two extremely similar-looking
headstander species. Initially the very
slender individuals were thought to be
males and the more high-backed
specimens females; but headstander
specialist Thomas Johannes was quick to
pointout theerror.Thehigh-backed fishes
with the stripedpatternon thebackare in
fact
Pseudanos trimaculatus
, and the
slender specimens are
P. gracilis
. The
purpose of this mimesis –mimesis is the
term used where a species imitates
another, non-poisonous one; if a
Pseudanosgracilis
poisonous species is imitated by a non-
poisonousone then the term ismimicry–
is totally unclear. Perhaps the two species
have a different dietary spectrum and
thus benefit from the protection of the
shoal without having to share their food
with too many conspecifics. The short
periodsof observation in theaquarium to
date haven’t provided any indication of
the reason for themimesis, either. Be that
as it may, the two species can be kept
together andwill swim aroundpeacefully
together.
Abramiteshypselonotus
Venezuela
