NEWS113
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thatthesurvival rateoftheyoungcatfishes is
around 80% higher when cichlids (usually
Copadichromis pleurostigmoides, Cteno-
pharynxpictus,
and
Rhamphochromissp.
) are
in the nest. How so? Well, the majority of
predatoryfishes inLakeMalawipreferyoung
cichlids to young catfishes as food. So the
young catfishes benefit fromhaving young
cichlids living in theirnest!
Anothercuckoo fish
Ithas recentlybeendiscovered thatanother
catfish in Lake Malawi, the Sapuwa,
Bathyclarias nyasensis
- known to the local
people as Bombe - acts as abroodparasite
on the Kampango. The young
Bathyclarias
are completely accepted by the parent
Kampango.Thismeansthattheyarenotonly
protected, but also fed. Female
Bagrus
meridionalis
produce unfertilized "food
eggs" to feed their young, and such eggs
have been found in the stomachs of all
young
Bathyclarias
living in Kampango
nests.Kampangomalesalso feed theyoung,
mountingexpeditions tobringback insects,
young crabs, etc, which they expel in
particulate form via their gill slits and thus
feed theyoung.
Kampango nests that are home to young
Bathyclarias
contain very few, if any,
Kampango young. It is not knownwhether
the parent
Bathyclarias
spawn over
Kampangonestsandtheiryoungthenhatch
sooner than the Kampango eggs and eat
theirstep-siblings,orwhethertheKampango
nests are invaded by older
Bathyclarias
fry.
One thing is certain, however: the
Bathyclarias
/Kampangorelationship isatrue
parasite/host relationship, that acts to the
detrimentof theKampangos.
And those,Dear Reader, are just a coupleof
stories about a Malawi cichlid. Doesn't this
demonstrate that these fishes have a lot
more tooffer than justattractivecolors?
Bathyclariasnyasensis,
theSapuwa,practicesbroodparasitismonBagrusmeridionalis, theKampango..
Bathyclarias nyasensis
can grow rather large,
with lengthsof up toameter known.
Bagrus
as foster parents rather than on
youngcatfishes.
The lightning-fast color change in
Pseudotropheus crabro
thus doesn't serve to
fool the Kampango. The color changemay
serveeither for intraspecificcommunication
or simply as camouflage against predators.
Asalreadymentioned,
P.crabro
prefersto live
in caves, where a dark-colored fish will go
virtually unnoticed and undoubtedly be
more difficult for predators to capture. The
striking hornet-like coloration is, however,
assumed by
P. crabro
when it wants to be
recognizedasacleaner.Aseven iftheHornet
Cichlidexhibitsdarkcolorationonlynowand
then and for no apparent reason, then at
such times itwill be safer frompredators,at
least tosomeextent.
Fish lice can transmit serious, possibly fatal
diseases to fishesattackedby them.Perhaps
this is thekey tounderstandingwhya large
fish like
Bagrus meridionalis
tolerates the
theft of its eggs and youngby
P.crabro
.The
ongoing threat from
Argulus
is apparently
reallyserious!
Fosterparents
It has already been mentioned that
numerous young cichlids share the
Bagrus
nestand"misuse"theparent
Bagrus
asfoster
parents. A study (M
C
K
AYE
, 1985) has shown
Thereareeightspeciesof thegenus
Bathyclarias
inLakeMalawi.
B.nyasensis
is themost frequent.
Literatur
:
Konings,A. (1989)
:Malawi Cichliden in ihrem
natürlichenLebensraum.VerdujinCichlids,
Zevenhuizen
McKaye,K.R. (1985)
:Cichlid-catfish
mutualisticdefenseof young inLakeMalawi,
Africa.Oecologia (Berlin) 66:358-363
Stauffer, J.R., Jr.&W.F.Loftus (2010):
Brood
parasitismof abagrid catfish (Bagrus
meredionalis) bya clariid catfish (Bathyclarias
nyasensis) inLakeMalawi,Africa.Copeia2010
(1):71-74
