NEWS 115
6
Nematobrycon lacortei
male.
Nematobrycon amphiloxus
was based.
Hence
Nematobrycon amphiloxus
is now
regarded as no more than a synonym of
N.
palmeri.
Geographical isolation
It cannot be ruled out that the Emperor
Tetra is currently undergoing a speciation
phase and that the dark amphiloxus is
already in the process of becoming a
distinct species. All emperor tetras live in
small forest pools that are linked to the
upper reaches of the rivers of the
Colombian Choco region only during
periods of inundation.
In the case of
N.palmeri
it is the drainage of
the Rio San Juan and Rio Atrato, and in the
case of
N. lacortei
the Rio Calima. The San
Juan and the Calima do indeed unite
eventually, but the main rivers are
insuperable barriers to the inhabitants of
forest pools. They cannot come into
contact with one another.It is likely that the
populations of the typical
N. palmeri
and
the dark
N. amphiloxus
were also originally
separated in this way. But within historic
times the Spanish colonial rulers dug a
canal between the Rio Atrato and the Rio
San Juan. One can well imagine that such a
canal, containing still, almost stagnant
water,would not represent a serious barrier
to a species such as the Emperor Tetra. And
thus the originally isolated populations of
the Atrato and the San Juan probably
became mixed together again through the
influence of Man.
It can be regarded as certain that the
emperor tetra species scientifically
described to date are closely related to one
another. There are no barriers to
hybridization between
N. palmeri
and
N.
lacortei
in the aquarium. Anyone lucky
enough to obtain wild-caught stocks
should always breed the strains true to
type.It is very probable that there are as yet
unknown
Nematobrycon
populations in
the drainages of the numerous rivers of
south-western Colombia.
Surprise!
But there is also at least one species of
characin found outside Colombia that can
perhaps be assigned to the emperor tetra
group. This species, which is as yet
undescribed scientifically, originates from
Brazil (unfortunately no more precise
details are available). The adipose fin is
absent, as in
Nematobrycon
, but the central
prolongation of the caudal fin is also
lacking. The caudal fin is more like that of
Inpaichthys
, the Royal Tetra, which can be
distinguished from
Nematobrycon
by two
Courting male
N. palmeri
characters: a caudal fin lacking any central
prolongation and the possession of an
adipose fin.
In the aquarium
The maintenance of
Nematobrycon
species
is easy, and feasible even for beginners.
These fishes like richly-decorated aquaria
with lots of plants.The substrate should be
dark, as then the colors of the fishes will be
seen at their most brilliant. Emperor tetras
are somewhat territorial among them-
selves. They may like to swim in a loose
group some of the time, but males also
defend small spawning territories. Hence
these fishes are best kept in a group of 10
or more individuals in aquaria with a
length of 50 to 60 cm upwards. Quite small
tanks with a volume of a few liters are
adequate for breeding. If the fishes are left
to spawn regularly then they can be bred
very effectively,easily producingmore than
150 young per pair per spawning. If these
fishes don't spawn regularly then many of
the eggs are non-viable.
Emperor tetras are peaceful towards other
species. Hardness and pH are unimportant
except for breeding. All the usual foods for
ornamental fishes are eagerly accepted.
All in all, emperor tetras are not only
attractive but also very interesting fishes.
Sure, the novice will initially buy them
largely for their striking appearance, but
even the advanced aquarist can undertake
numerous interesting studies of them.
Literatur
:
Weitzman, S. H. & W. L. Fink (1971): A new
species of characid fish of the genus
Nematobrycon from the Rio Calima of
Colombia (Pisces, Characoidei, Characidae).
Beaufortia 19 (248): 57-77
