Behav­iour

The behav­iour of the licorice gouramis is a story in itself

P.nagyi male going into his 'cave' (photo H.Schoubye)

Parosphromenus are small, cave inhab­it­ing labyrinth fish with a fully devel­oped labyrinth organ. The high oxy­gen con­tent of their nat­ural habi­tats in flow­ing waters makes it unnec­es­sary to use the labyrinth often. This is still the case in the aquar­ium. Some fish never use the labyrinth. How­ever the males of most species build more or less rudi­men­tary bub­ble nests in their caves and take up air from the sur­face fre­quently dur­ing this period. In their nor­mal life they do not use the labyrinth unless a sig­nif­i­cant dete­ri­o­ra­tion of the envi­ron­men­tal para­me­ters forces them to do so.

They are quiet fish, which are not con­stantly in motion. They do not like the com­pany of fast, hec­ti­cally swim­ming fish. On the other hand some small fish, which use the open water space (like a small troup of Boraras species) can give them the feel­ing of safety from preda­tors and draws them out of their hid­ing places more often. Indi­vid­ual fish seem to seek fos­hel­ter and they often stick closely to leaves, wooden branches or a cave wall. They often show a float­ing way of swim­ming and stop fre­quently to per­form strange slow motions around the eye axis. Until now we have no idea what this behav­iour means.

Depend­ing on their mood or behav­ioral con­text the fish show more or less sig­nif­i­cant colour or changes in liv­ery. Besides the nor­mal dress, in which the stripes are clearly pro­nounced, a sig­nif­i­cantly darker aggres­sion dress and the most colour intense courtship dress can be dis­tin­guished – the dif­fer­ent colour pat­terns can change within sec­onds. The so-​called ”sexy eyes”, named by Diet­rich Schaller, are very strik­ing. They com­prise a broad inclined black bar, which indi­cates the imme­di­ate spawn­ing mood, espe­cially in females, but also in males. It is also remark­able that most of the females lose almost all colours dur­ing courtship and take on a pale, beige or even yel­low dress. The form P. palu­di­cola Wakaf Tapei is an excep­tion in this respect: although other palu­di­cola forms have pale courtship dress in females, in this par­tic­u­lar form the females become dark – a dif­fer­ence which made J. Vierke and P. Finke sus­pect that it might be a sep­a­rate genus. How­ever, until there is genetic proof for this, one can­not be sure about it. At least this par­tic­u­lar­ity could even­tu­ally indi­cate a rel­a­tively advanced speciation.

Zwei Mänchen in agressionskleid (photo H.Schoubye)

Strik­ing sim­i­lar­i­ties, but also dif­fer­ences between the species are reflected in their courtship behav­iour. We can dis­tin­guish 3 groups or types accord­ing to the posi­tion the male takes dur­ing courtship: head-​down, head-​up and hor­i­zon­tal courtship. Most Parosphromenus show head-​down courtship. The male stands beside the female, almost com­pletely head down and spreads all fins. All forms of the bin­tan– and har­vey– fam­ily belong to this group, but also species like P.anjunganensis or P.filamentosus. Some species with par­tic­u­larly log dor­sal fin like P.paludicola, P.deissneri or P.quincedim per­form a rather hor­i­zon­tal courtship.

Filamentosus female with sexy eyes (photo Wimmer)

The two lean Parosphromenus species, P.parvulus and P.ornaticauda show, in addi­tion to their dif­fer­ent body shape and head-​up courtship, a par­tic­u­larly strik­ing behav­iour in con­trast to all other mem­bers of the genus: very fast, courtship dances over a wide area. The male sur­rounds the female in a zig-​zag cir­cle tak­ing one or two sec­onds. For all other licorice gouramis the courtship is much calmer and only a lit­tle room is needed. This behav­iour also sup­ports the assump­tion that these two species form a sep­a­rate group in the genus Parosphromenus or even a sub-​genus. A strange inter­me­di­ate posi­tion is shown by P.sumatranus. This species is often slim, like a lean Parosphromenus form and does head-​up courtship (with­out zig-​zag dance), too. But this species shows the typ­i­cal striped dress like the other Parosphromenus. There­fore we assume that forms, which have been very sim­i­lar to these fish, might have played a par­tic­u­larly inter­est­ing role dur­ing the evo­lu­tion of the liquorice gouramis. But there also seem to be pop­u­la­tions of this species with a higher back. Still many mys­ter­ies are to be revealed here.

(PF)

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