Scleractinian corals rely on a mutualistic relationship with microalgal symbionts for growth and survival. Abnormally warm waters cause the expulsion of symbionts, resulting in coral bleaching and potential mortality. Assisted evolution strategies are currently being explored to accelerate naturally occurring processes to increase holobiont heat tolerance and are promising for active reef restoration. In this study, we examined whether cultured symbionts conditioned to withstand bleaching temperatures (heat-evolved) can be acquired by a variety of scleractinian coral larvae and juveniles. We also assessed the minimum density required for optimal uptake of wild-type (WT) and heat-evolved (HE) symbionts by systematically inoculating four coral species (acroporid and non-acroporid) with Cladocopium and Durusdinium WT and HE at different exposure densities (larvae = 10, 10², 10³, 10⁴ cells mL⁻¹; juveniles = 10³, 10⁴, and 10⁵ cells mL⁻¹). Our results showed that the uptake of both types of Durusdinium was significantly higher than for Cladocopium in all coral species, with Durusdinium showing uptake even in the lowest density treatments. In contrast, Cladocopium, particularly HE, showed minimal to no uptake until 10⁴ cells mL⁻¹. These results offer valuable insights for the optimization of symbiont inoculation processes for reef restoration.