These data were generated in support of the manuscript: Bilodeau SM and Hay ME (2026) Recent stresses and maladaptive behavior: a specialist coral predator does not choose healthy over bleached corals despite strong impacts on consumer fitness. Marine Ecology Progress Series. https://doi.org/10.3354/meps15221 We investigated the host preferences of corallivorous nudibranch Tenellia lugubris in Moorea, French Polynesia and the consequence of those preferences. We assessed nudibranch preference for various species of corals, bleached and unbleached corals, and corals occupied by co-occurring crabs and snails. We measured the nudibranchs' ability to chemically respond to healthy and bleached coral cues in a flume and their growth and survival on bleached or healthy corals. We also evaluated nudibranch occurrence in the field, egg laying, and the adverse feeding effects that these corallivores have on Porites corals. These data were collected in 2021 and 2025.