Identification of Sturisoma aureum, Sturisoma festivum and Sturisoma panamense
The confusion of the identity of Sturisoma aureum and Sturisoma festivum is a common and wide spread mistake. This confusion originate on the one hand from the typelocality of S. festivum (Maracaibo basin) where commercial fish trade is lacking for years. On the other hand there was one publication with a faulty identification of a specimen of S. festivum as S. aureum. A long time nobody scrutinised, but adopt it and contributes the distribution of this misidentification. Very similiar is an other faulty identification and its publication that is the origin of the confusion of Sturisoma panamense and Sturisoma festivum.
With a closer view on all three species it is not very difficult distinguish them clearly.
Most characteristical are the differences in the pectoral and dorsal fins that everybody is able to relate.
principally offered as offspring. Unfortunately the impressive species Sturisoma panamense is not in trade yet.
Dorsal fin
Pectoral fins
S. aureum
Spine nearly straight, in maturity slightly bent at the tip.
The ratio of body height to fin size is about 1:2.
No filamentous extension.
Spine slightly bent.
The ratio of body width to fin size is about 1:1.5.
No filamentous extensions.
Dorsal fin
Pectoral fins
S. festivum
Sometimes slightly S-curved shape of the spine.
Bent from the middle of the fin.
Ratio of body height and fin size is about 1:2.5.
At least a small filamentous extension of the spine.
More or less straight spine.
Ratio of body width and fin size is up to 1:2.
At least small filamentous extensions of the spines.
Dorsal fin
Pectoral fins
S. panamense
The spine is straight.
The ratio of body height and fin size is up to 1:3.
No filamentous extension.
The spine is nearly straight.
The ratio of body width and fin size is about to 1:2.
No filamentous extensions.
Adolescent specimen are hard to identify correctly. Mostly the size of the dorsal fin gives a hint for the species they belong. From beginning of maturety the listed differences are clearly visible for all the three species.
Unfortunately Sturisoma festivum is a very heterogenous species with different types of body shape. If you have a closer view you will find specimen with a slender body and very large fins whose spines are filamentous elongated. But you also will find ungraceful specimen with comparatively small fins that are not elongated at all.