The smalltail shark is often caught as bycatch and may be used for meat, fins, liver oil, cartilage, and fishmeal.

Italian naturalist Camillo Ranzani published the first scientific description of the smalltail shark in an 1839 volume of Novi Commentarii Academiae Scientiarum Instituti Bononiensis.

[9] The Pacific smalltail shark (C. cerdale) was once mistakenly synonymized with C. porosus, until 2011 when José Castro resurrected it as a distinct taxon.

The mouth bears short furrows at the corners and contains 13–15 tooth rows on either side of both jaws (usually 14 upper and 13 lower).

The upper teeth are tall and triangular with strong serrations, becoming increasing oblique towards the sides.

[4][5] The dermal denticles mostly do not overlap; each has three to five horizontal ridges leading to posterior teeth, with the central one the longest.

[11] The known range of the smalltail shark extends from the northern Gulf of Mexico to southern Brazil, excluding the Caribbean islands (aside from Trinidad and Tobago).

[1][13] This species has not been reported east of the Mississippi River in the past 50 years, despite historical evidence of a nursery area off Louisiana.

[1] The smalltail shark forms large aggregations segregated by sex, with the males generally found deeper than the females.

Opportunistic in habits, the dietary composition of this shark generally reflects what is most available in its environment; off northern Brazil, the most important prey species are the croakers Macrodon ancylodon and Stellifer naso.

Known nursery areas occur in shallow, murky waters off northern Brazil and Trinidad, where many bays and estuaries provide shelter and food.

[5][15] Harmless to humans,[11] the smalltail shark is caught incidentally by gillnet and longline fisheries throughout its range.

[5] Off northern Brazil, substantial numbers are caught by gillnet fisheries targeting the Serra Spanish mackerel (Scomberomorus brasiliensis).

This apparent decline is thought to have resulted from increasing fishing effort, the large proportion of juveniles captured, and the shark's low reproductive rate.

Although the smalltail shark was ostensibly given protection by inclusion on the 2004 Official List of Endangered Animals in Brazil, fishing remains effectively unmanaged.