Scorpiodoras calderonensis differs from its congeners S. heckelii and S. liophysus by having secondary gas bladder terminally extended by elongate diverticulum 'recurved like the whip of a scorpion' (vs. secondary gas bladder absent in S. liophysus and without elongate terminal diverticulum in S. heckelii). It is further distinguished from S. heckelii by having a relatively small eye, diameter 63-93% of interorbital width (vs. relatively large eye, diameter 91- 129% of interorbital width) and from S. liophysus by possessing relatively shallow scutes, depth 41-59% of body depth near anal-fin origin (vs. 61-72%) (Ref. 86601).

Description: anal fin iv-v,7-9 (Ref. 86601).