NEWS108
8
Although there is nothing to that effect in the aquariumhobby literature
on livebearing toothcarps (see bibliography for themost important and
most widely available handbooks), current wisdomon the Internet, and
even in trainingmanuals for those applying for apet-trade license, is the
abstruse recommendation that livebearing toothcarpsarealwaysbestsold
in the ratioof onemale to three females.
Extramales,extra
females,pairs??!!
What is the rightway tokeep
Guppy,Platy,&Co?
byOliverHelkerundPeterMerz
Evergreens
his isbased largelyon thepermanent
display and courtship by themales.
An excess of females supposedly spreads
thispressuremoreevenlyand thusminimi-
zes thenegativestresson the individual fe-
males.
Whatdoessciencehave tosayabout it?
In thepastprecisely theoppositehasbeen
stated in several scientific works, namely
that an excess ofmales ismuch easier on
the females.
Thesestudieswereconducted in the1940s
and1950s. Theobject of thework was to
establish thescientificprerequisites for the
optimal laboratorymaintenance of Platies
and Swordtails, as it hadbeendiscovered
that certain crosses between Platy and
Swordtail resulted in cancers in the off-
spring.Thiswas a revolutionary discovery
thatpermittedagiant leap forward incan-
cer research. Millions of people afflicted
with cancer owe their lives to the
knowledge obtained from these experi-
mental organisms.
Itwas found that in Platies the aggressive
interactions between males and females
were comparable, ie females nipped one
another justasoftenasmales,and thiswas,
moreover, independent of whether they
werekept in single-sex (maleor female) or
mixed-sexgroups.
Inaddition,whenPlatiesandSwordtailsare
crossed behavioral characteristicsare inhe-
rited true to type. This means that even
T
VariatusPlaty,
Xiphophorusvariatus
,malewithSimpson finnage. All photos:FrankSchäfer
Endler'sGuppy ”ViennaEmerald”.
Green Swordtail,
Xiphophorus hellerii
, spotted
wild form ”Guentheri”.
Swordtails that owe their coloration to a
Platy in-crossexhibit typical,species-speci-
ficSwordtailbehaviorandare indistinguis-
hable frompure-strainSwordtails in this re-
spect.The same applies to Platies: they al-
ways retain their species-specific Platybe-
havior, evenwhen they have Swordtail in-
crosses in their ancestry.
Whathappenswithanexcessofmales?
If you stop and think a little aboutwhy an
excessofmales shouldbeeasieron the fe-
males,thenyoucanestablish thisquitesim-
ply for yourself without needing to read
anydrystudies orneeding tobeabiologist
at all.
If you keep several males in an aquarium,
theneachmalewill try toattract theatten-
tionof femalesandsecureaharem forhim-
self by competing with other males. The
majority of the time the males are busy
among themselves and don't havemuch
