parvu­lus

P. parvulus Tangkiling  Foto: Olivier Perrin“

First descrip­tion:Ein neuer Labyrinth­fisch von Bor­neo — Parosphromenus parvu­lus nov. spec. Das Aquar­ium 13 (120):247250.

Char­ac­ter­is­tics: total length max. 3.5 cm. Dor­sal struc­ture: X-​XI, 56, total 1517, anal fin: VIII-​IX, 1011, total 1820. Much leaner, with a less high back com­pared to the other species, with the excep­tion of P.ornaticauda, which can be regarded as a “twin species”. Adults appear to have a wide, rather then high, oval cross-​section, seen from the front. Like ornat­i­cauda it dif­fers also in behav­iour and col­oration. The ♂ shows char­ac­ter­is­tic, nagyi–like body col­oration in breed­ing coloura­tion: lower half of the body very dark to black, upper half yel­low to yellow-​brown. Also the pat­terns of the unpaired fins dif­fer, like those of P.ornaticauda, from the typ­i­cal pat­terns in this species: dor­sal and anal fin are black with red spots.

Depend­ing on the local­ity, there are var­i­ous degrees of very lumi­nous white iri­des­cent edges. The ven­tral fins are trans­par­ent, the cau­dal fins are almost colour­less or dark-​blackish. Nup­tial coloura­tion is shown often, but not as con­tin­u­ously as by P.ornaticauda. The species-​typical striped pat­terns can be seen some­times in sex­u­ally mature males, but mainly in tran­si­tion to breed­ing colours. The female shows the striped pat­terns most of the time, and unlike ornat­i­cauda, never an appear­ance which is almost iden­ti­cal with the nup­tial colours of the male. Regard­ing vari­a­tion within of the species, please refer to “Distribution/​Occurrence”.

Sim­i­lar species: in males con­fu­sion is not pos­si­ble; it can be dis­tin­guished by colour and pat­terns from the struc­turally sim­i­lar species P.ornaticauda In females in nor­mal dress, the fish can be con­fused with P.ornaticauda. Small fry are almost indis­tin­guish­able. Due to the body struc­ture, the risk of con­fu­sion with other species of licorice gouramis is low.

Occur­rence /​Dis­tri­b­u­tion: South­ern Cen­tral Bor­neo: Kali­man­tan Ten­gah, in the area of Ban­jar­masin. First dis­cov­ery took place 250km NW of this city near Palan­gan in the catch­ment area of the Mentaya-​River. Later ex pedi­tions have shown that the species has a much wider dis­tri­b­u­tion thanwas assumed. So it was found by H. Linke and J. Knüp­pel in 1988 in Palangkaraya; it was already clear then that the area of occur­rence is much big­ger as orig­i­nally thought. Later fur­ther local­i­ties were found, among oth­ers by Linke and O. Per­rin. Thus P.parvulus turned out to be the licorice gourami with the (so far) largest known area of distribution.

How­ever the fish caught there showed a small but sig­nif­i­cant vari­a­tion, espe­cially con­cern­ing the pat­terns of the fins. So the fish from the vicin­ity of Tangk­il­ing had the clear­est white lumi­nous edges in dor­sal and anal fin and also a sig­nif­i­cant red dot pat­tern mainly in the dor­sal fin, while the pop­u­la­tion, exist­ing near Babu­gus has a more mod­est coloura­tion (both col­lected by H. Linke).

Threat: Even P. parvu­lus is highly endan­gered today by relent­less destruc­tion of its habi­tats, despite the fact that more loca­tions are known than at the time of its dis­cov­ery. While some of the older local­i­ties have already dis­ap­peared, many of the lat­terly dis­cov­ered places have become more or less affected by human activ­i­ties. The ongo­ing progress of for­est destruc­tion increas­ingly threat­ens for­merly unaf­fected remain­ing wet­lands, which are prone to trans­for­ma­tion to short-​term use as farmland.

Discovery/​First import:dis­cov­ered near Palan­gan and­brought to Europe by Edith Korthaus and Dr. Wal­ter Foer­sch in 1978. The first descrip­tion was made in Ger­many in con­nec­tion with this first import.

Trade:before 2005 P. parvu­lus was not seen in trade at all. The few fish, which were then in the aquar­ium stock, orig­i­nated from pri­vate imports or were bred from these. From 2006 onwards, some exports or imports were known and mean­while this species is some­times avail­able in trade. Com­pared to ornat­i­cauda it is only offered in small num­bers in pet shops, but – because the fish is very unim­pres­sive there – they are doomed even faster then its twin species.

Care /​Breed­ing: con­cern­ing care the fish dif­fers lit­tle from P.ornaticauda, but some­times it seems to be less pre­car­i­ous. How­ever, breed­ing this species is still a mys­tery, as reli­able breed­ing (and car­ing) cou­ples are not the rule. Also this species prefers caves with a small diam­e­ter, in which they can lay their often small clutches (825 eggs). Also for parvu­lus a low germ den­sity is the pre­req­ui­site for the sur­vival of the eggs. For this rea­son breed­ing suc­cess has often occurred only after a drop of the pH value to 4 or even less. G. Kopic reports of breed­ing suc­cess at pH 2.7. But this exper­i­ment should not be repeated with­out any good rea­son. Kopic also reports that lar­vae had dif­fi­cul­ties free­ing them­selves from the egg shells. This is why arti­fi­cial breed­ing with­out the car­ing male poses even more risk than it usu­ally does. With nat­ural care by the male at higher pH val­ues, com­plete clutches often dis­ap­pear overnight, but there have been suc­cess­ful broods at pH 6.0 and more. Low germ den­sity often, but not always, cor­re­sponds with low pH val­ues. Also the con­duc­tiv­ity has to be low, prefer­ably below 35 microSiemens/​cm, because oth­er­wise the clutches would not stick to the caves’ ceil­ings, and the eggs would fall down and per­ish. Like P.ornaticauda, P. parvu­lus is not a beginner’s fish.

Behav­iour /​Par­tic­u­lar­i­ties:like its twin species, P.parvulus per­forms a head-​up courtship. Caves are accepted at the bot­tom, near the sur­face or in suit­able posi­tions at any place in the plant lay­ers. Also here, as for its twin species, the area of its activ­ity is much greater than other licorice gouramis, because the P.parvulus male does a spec­tac­u­lar courtship dance, which we have already described for the other species: first the male presents its flut­ter­ing fin edges and then zig-​zags around a female. How­ever the strik­ing colour approx­i­ma­tion of the females to the male´s nup­tial plumage, which can be recog­nised dur­ing the courtship behav­iour of P.ornat­i­cauda, does not take place with P.parvulus. Still, both species stand out clearly as twins within the genus, due to their struc­tural and behav­ioural par­tic­u­lar­i­ties. Even­tu­ally they may form a spe­cial group, together with the slim form of P.sumatranus, which would indi­cate an evo­lu­tion­ar­ily closer relationship.

Parosphromenus parvulus couple Copyright Helene SchoubyeParosphromenus parvulus male Copyright Helene SchoubyeParosphromenus parvulus male Copyright Helene SchoubyeParosphromenus parvulus young male Copyright Helene SchoubyeParosphromenus parvulus male Copyright Helene SchoubyeParosphromenus parvulus 'Babugus' male Copyright Peter FinkeParosphromenus parvulus male Copyright Helene Schoubye

Parosphromenus parvu­lus female

Parosphromenus parvulus female Copyright Helene SchoubyeParosphromenus parvulus female Copyright Helene Schoubye

Parosphromenus parvu­lus ‘Tangk­il­ing’ pho­tographed by Olivier Perrin

Parosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier PerrinParosphromenus parvulus 'tangkiling'Copyright Olivier Perrin

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