We evaluated cui-ui,Chasmistes cujus, swim-up success, time of hatching and swim-up, and size of larvae at swim-up under four fluctuating temperature regimes (8.9–15.0, 12.2–18.3, 15.0–21.1, and 17.8–23.9° C). The greatest swim-up success was at the 8.9–15.0° C regime and the lowest at the 15.0–21.1° C regime. Hatching and swim-up time varied inversely with incubation temperature. The largest (and presumably the most fit) larvae were in the 8.9–15.0° C treatment, whereas the smallest were in the 17.8–23.9° C treatment. Cui-ui appeared best adapted to the coolest of the four temperature regimes.