Finlets are small fins located on the dorsal and/or ventral midline of a fish, between their dorsal or anal fin and the caudal fin. For the most part, finlets are observed in pelagic, high-performance swimming species, such as scombrids and carangiforms, and finlets appear to have evolved independently in several lineages of teleost fishes. Recent computational work on tuna and mackerel has shown that finlets increase a swimming efficiency and that rows of finlets in series can reduce drag. However, Polypterus, in the family Polypteridae, is a member of the most primitive living group of ray-finned fishes, and species may have between seven and twelve finlets that extend along the dorsal body margin. The function of these finlets during locomotion is unknown. In order to investigate finlet function in Polypterus senegalus, we (1) investigated their morphology using uCT scans and dissection, and (2) studied finlet movements during both steady and unsteady locomotion using high-speed video. Polypterus finlets each have an anterior spine, which allows for their elevation and depression. This contrasts with tuna finlets, which only oscillate laterally and cannot be actively elevated or depressed significantly. We use DeepLabCut to track and measure various kinematic variables of the body and finlets (e.g. swimming behavior and frequency, finlet lateral excursion angle and elevation angle) to determine if finlets provide a hydrodynamic function for P. senegalus during steady and unsteady swimming. Preliminary studies suggest finlets appear to be depressed during acceleration but are elevated during slow speed swimming. Likewise, P. senegalus finlets increase in dorsal elevation angles and lateral excursion from anterior to posterior along the length of the body, and finlet height and lateral excursion vary among swimming behaviors.