NEWS107
46
riumGlaserhasnowmanaged to importa
second batch of larger (8-10 cm) speci-
mensof this lovely silverdollar fromBrazil.
Althougheach specimenexhibited indivi-
dualdifferences instriping,the fisheswere
alreadysexuallydifferentiated,ieno longer
small juveniles.Metynnisspeciesareherbi-
vores and usually grow to around 15 cm
long.Maleand femalediffer in the formof
the anal fin. Because amember of staff at
Hyphessobrycon
cf.
melanostichos,
male
fishesarepopularlyknownas shoaling fis-
hes in the hobby, but this is both techni-
cally and linguistically incorrect. Rather
theyare social fishesandhence shouldbe
kept ingroupsof10ormore individualsso
that they candevelop their full repertoire
of intraspecific behavior. Individuals kept
in smaller groupswill bedisappointing in
theircoloration.
Hyphessobryconmelanosti-
chos
was first scientifically described in
and their sizemakes themworth catching
by rodand line,but youhave tobewareof
theirteeth,astheybitehardandcausedeep,
bleedingwounds. Until a few years ago it
was thought that there were just two or
threeverywidespreadandvariablespecies.
In the last10years,however,scientistshave
devoted themselves to the genus and at
present12speciesof
Hoplias
arerecognized,
and thereareundoubtedlya fewmorespe-
ciesstill tobediscovered.
The species shown herewas imported by
AquariumGlaser fromVenezuela,andmay
possiblybe
Hoplias teres
. In any case, it is a
world first import.The fisheswere around
15-20 cm long and extremely aggressive.
When a small stick was used to carefully
guide them into a favorable position for
photography,theybit itsohardthat I imme-
diatelyabandonedtheattempttoavoidany
riskof thevaluable fishes injuring themsel-
vesasa resultof theirattacks.
Hyphessobrycon
cf.
melanostichos,
female
Hyphessobrycon
cf.
melanostichos,
courtship.
Hoplias
cf
.teres
Photo:Andreas Jekel
AquariumGlaserhaspurchasedsomespe-
cimens for himself, thenperhaps in a year
or two, when the fishes are full grown,
therewillbemore information to reporton
them.
Hyphessobrycon
cf.
melanostichos
AquariumGlaser has obtained this at first
glance somewhat unremarkable characin
notonlywildcaughtbutalsocaptivebred.
It belongs to the extensive phylogenetic
assemblageof theBlacklineTetra
Hyphes-
sobrycon scholzei.
On further examination,
however,thisaround4cm long fishproves
to be a real eye-catcher, as during court-
ship it develops beautiful red fins and a
fire-redback.
This little tetra exhibits a behavior typical
of themajorityof small tetrasofaquarium-
hobby importance: these fishes live in
loosegroups and themales occupy small
temporary territories for spawning. Such
2006.Todate it isknownonly from theRio
DozedeOutubro,asmall river in theupper
drainage of the Rio Tapajos. It cannot be
confirmed at present whether fishes
shown here are actually identical with
H.
melanostichos
, but there are a very large
numberofpointsof agreement.
Hoplias
cf.
teres
Predatorycharacinsofthegenus
Hoplias
are
foundalloverSouthAmerica,andareknown
variouslyas trahirasorwolf characins.They
areancient fishes,very similar to theance-
storsof themoderncharacinsthat lived100
millionyearsago.Trahirasgrow tobetween
30and100cm longand feedexclusivelyon
other fishes.Becausetrahiraspossessanau-
xiliary respiratorysystem thatenables them
to take inandbreatheair from thewater's
surface, theyareoften theonly fishes tobe
found in drying-up residual pools, where
theyhaveeatenall theother fishesandare
waiting for better times. Trahiras are tasty
