We quantitatively sampled the threatened Inflated Heelsplitter (Potamilus inflatus) in the Amite River, Louisiana, U.S.A., and sectioned shells to study its life history, as well as electrofishing the river to determine the relative abundance of its host fish. Inflated Heelsplitters are currently limited to a 40 km stretch of the Amite River, east of Baton Rouge, although they are also found in two rivers in northwest Alabama. Densities averaged 0.1 m⁻², with an aggregated dispersion pattern, making them the sixth most abundant species out of 15 species found in quantitative samples. Inflated Heelsplitters mature after 1 y, live for 8 y, and have a rapid growth rate (K  =  0.69/y). The average life span of eight other mussels in the Amite River is 24 y, and average age at maturity is 3.6 y. Sexual dimorphism may occur in Inflated Heelsplitters as it does in the related Bluefers (Potamilus purpuratus), with males reaching larger sizes. Inflated Heelsplitters have an opportunistic life history strategy (Haag, 2012), which may be well adapted to flashy rivers and low population densities. It is however a long term brooder, which has been linked to higher chances of extinction (Vaughn, 2012). The Freshwater Drum (Aplodinotus grunniens), the fish host of the Inflated Heelsplitter, was the 17th most abundant out of 44 fish species sampled in the Amite River. Its relatively rare host fish, anthropomorphic disturbances from upstream gravel mining, or increased urbanization of the watershed may be important in explaining the threatened status of the Inflated Heelsplitter.