As is well known, the royal farlowellas (Sturisoma and Sturisomatichthys) were reclassified in 2019, resulting in some regrouping. Several species previously classified as Sturisoma now belong to the genus Sturisomatichthys. According to Londoño-Burbano & Reis, 2019, externally recognizable differences between the two genera are the irregular, numerous central ventral plates that are not arranged in defined series in Sturisomatichthys (as opposed to three clearly arranged series of developed central ventral plates in Sturisoma); the possession of dark spots on one or all dorsal, pectoral, pelvic or anal fins in Sturisomatichthys (as opposed to lack of spots in the fins in Sturisoma); and 13-18 plates on the median row of plates in Sturisomatichthys (as opposed to 20-21 plates on the median row in Sturisoma). Grammar: the genus name Sturisoma is neuter, species names that are adjectives must therefore end in -um, Sturisomatichthys is masculine, species names that are adjectives must therefore end in -us.
Few determinations are discussed as much in aquarium circles as the distinction between Sturisomatichthys aureus and S. festivus. In terms of color, both species are largely identical and both come from Colombia, albeit from different river systems. However, there is a difference that is already clearly recognizable in juveniles from a total length of approx. 5 cm: in S. festivus, the first rays of the dorsal, pectoral and ventral fins are clearly elongated. Over the decades, however, the two species have almost certainly been inadvertently crossed more frequently because the short-finned animals were thought to be females and the long-finned ones males. This easily explains why the old aquarium strains of S. festivus often look quite inconsistent. If you want to be sure of owning purebred animals, you should therefore always resort to wild-caught specimens.
In the very early days (in the 1980s), S. festivus was referred to as S. panamensis. However, this is another species that can be reliably distinguished from S. aureus and S. festivus by the fact that the dark longitudinal band along the middle of the body does not touch the dorsal fin (in S. aureus and S. festivus it does so very clearly). In S. panamensis there is only a small line from the longitudinal band to the base of the dorsal fin. S. panamensis is not represented in the trade (there are only occasional souvenirs from Panama by traveling aquarists, no exports). The species has no colour or other special features that make it desirable compared to S. aureus or S. festivus and is therefore restricted to the tanks of specialized enthusiasts only.
The care and breeding of Sturisomatichthys aureus does not present any particular difficulties. The animals are open-breeders and often lay their clutches on one of the aquarium glasses. The male guards the clutch until it hatches. The sexes are not always easy to recognize. Sexually active males have a “whisker” and slightly longer fins, the females are generally smaller. However, old females can also look like males and, conversely, there are males that look like females. It is often reported that Sturisomatichthys are capable of changing sex. This has not been proven, but of course it is not impossible either. Many marine fish species generally change sex in the course of their lives, but this is rare in freshwater fish. It has also been observed that two juveniles of Sturisomatichthys that are placed together in a new aquarium regularly develop into a pair.
Sturisomatichthys are generally peaceful towards other fish and also towards each other. However, adult males do not get along well with each other. The water values are of no great importance, but the animals like it warm (24-28°C). It is essential to ensure that these relatively slow eaters get enough food (greens of all kinds, food tablets, frozen food). The final size of S. aureus is around 20 cm, and they are often sexually mature at half this length.
For our customers: S. aureus has code 294503 (wild, 9-12 cm), 294513 (captive bred, 8-10 cm) and 294521 (captive bred, 4-6 cm) on our stocklist. The pictures for this post show 294503. Please note that we only supply wholesale.
Literature:
Londoño-Burbano, A. & R. E. Reis (2019): A taxonomic revision of Sturisomatichthys Isbrücker and Nijssen, 1979 (Loricariidae: Loricariinae), with descriptions of three new species. Copeia v. 107 (no. 4): 764-806
Text & photos: Frank Schäfer
