[2] The spottail pinfish was first formally described as Sargus holbrookii in 1878 by Tarleton Hoffman Bean with its type locality given as the Savannah Bank off Charleston, South Carolina.

[4] The genus Diplodus is placed in the family Sparidae within the order Spariformes by the 5th edition of Fishes of the World.

[5] The spottail pinfish honours the American physician and naturalist John Edwards Holbrook who wrote the Ichthyology of South Carolina published in 1855.

[10] Spottail pinfish are common to shallow waters (only as deep as 28 metres or 92 feet) near coasts, such as bays and harbors, though only rarely in brackish areas.

They prefer flat, vegetated bottoms such as beds of sea grass,[9] where they feed on a mixture of plants (such as Thalassia)[11] and small invertebrates.

Fish in breeding condition have been measured from 12.9 cm (5.1 in) and the gonads develop in the months leading up to spawning.