based dor­sal fin.
For the males it is struc­turally, and in terms of colour, eas­ily recog­nis­able due to the char­ac­ter­is­tic cau­dal: extended with a clear fil­a­ment, inner area brown/​red broad black fram­ing and a thin white/​blue edge. This edge and fram­ing appear again in the dor­sal and anal fin, which are brown/​red or blue/​green iri­des­cent with small or larger por­tions of the respec­tively other colour. Prob­a­bly these colour vari­a­tions indi­cate dif­fer­ent pop­u­la­tions. The ven­tral fins are green/​blue with long fil­a­ments. In spawn­ing mood,the females show the genus-​typical pale colour­ing, but notice­able coloured edges in the unpaired fins. The dor­sal fin is often edge­less, but it can have a fil­a­ment, as well (see photo Koomans). Also the cau­dal fin is pointed, but with a less dis­tinct fil­a­ment com­pared to the males.
Sim­i­lar species: in the ‚he risk of con­fu­sion with other licorice gouramis is very low, since no other forms or vari­eties are known, which have a sim­i­lar com­bi­na­tion of char­ac­ter­is­tics. Also the females can be dis­tin­guished fairly well from other licorice gouramis by the shape of the cau­dal fin, the long-​based dor­sal fin and often by faint colour pat­terns in dor­sal and anal fin. In any case, this is pos­si­ble when they show their courtship colouring.
Occur­rence /​Dis­tri­b­u­tion: P. fil­a­men­to­sus occurs in Kali­man­tan Ten­gah (Bor­neo, Indone­sia) in jun­gle river sys­tems near Ban­jar­masin. As with most other licorice gouramis, the exact extent of its range is unknown.
Threat: not known, but likely to be very high. As the extent of its dis­tri­b­u­tion is not known, it must be assumed that its exis­tence is highly endan­gered, because large-​scale destruc­tion of for­est habi­tats have occurred in the Ban­jar­masin area .Care /​Breed­ing: No spe­cial con­di­tions. P. fil­a­men­to­sus is one of the least spe­cialised licorice gouramis and it may be rec­om­mended, even to peo­ple who have lit­tle expe­ri­ence with this genus . Builds a large foam nest com­pared with other forms of the genus and can pro­duce large clutches (Kopic: up to 200 eggs), but in most cases far less (nor­mally adult ani­mals lay 50 – 70 eggs).
Behav­iour /​Par­tic­u­lar­i­ties: Per­haps the species with the most dis­tinct foam nest in the cave. To build it, the male picks up air from the water sur­face sev­eral times. Head-​down-​courtship. The court­ing males can develop a very smoky dark over­all col­oration. The female is species-​typical pale.