Although there are dozens of very similar species in the Apistogramma genus, new research has shown that the fish are very picky in selecting a partner of the same species.
According to a study by cichlid experts Uwe Romer and Wolfgang Beisenherz, which has just been published in the journal Ichthyological Exploration of Freshwaters, female Apistogramma cacatuoides prefer wild type males over anything else.
By keeping the females in aquaria and presenting them with a choice of sexual partners to mate with, the authors were able to determine which fish the females prefered.
Most females went for the inconspicous wild-type males of A. cacatuoides, including both wild fish and captive-bred F1 and F2 fish produce from wild stocks. They didn't fancy the gaudy males of the domestic strains we see on sale in the shops here.
They also chose to mate with members of their own species over closely related Apistogramma of other species, including A. juruensis, A. martini, A. panduro, or A. sp. "brustband".
Romer and Beisenherz claim that this supports the theory that despite their striking similarity in morphology and colouration, that many Apistogramma varieties do represent distinct species.
For more details see the paper: Romer, U and W Beisenherz (2005) - Intra- and interspecific mate choice of female Apistogramma cacatuoides (Teleostei: Cichlidae).
Ichthyol. Explor. Freshwaters, Vol. 16, No. 4, pp. 339-345, 3 fi gs., 2 tabs., December 2005.