Exploring light-effects of microalgal extract on zebrafish caudal fin cell regeneration for aquaculture applications

Microalgae represent a large group of photosynthetic microorganisms that produce a wide range of bioactive compounds as part of their metabolic processes. Many of these molecules have been reported to promote cell adhesion, migration and proliferation, indicating their relevant potential for treating skin injuries. In intensive aquaculture production systems, skin lesions in farmed fish, resulting from aggressive behaviour or suboptimal management practices, could increase their susceptibility to infections and diseases compromising their welfare and overall production efficiency. The present study focused on testing the effects of the green microalga Neochloris oleoabundans whole extract at different concentrations (1:16 and 1:32 dilutions) on cell proliferation and migration in AB9 zebrafish caudal fin fibroblast cells, showing enhanced wound healing after a 30-min treatment in constant darkness (DD; + 5–20% in wound closure in treated cells). As zebrafish cells and tissues are directly light-entrainable and thus, light-dependent reactions in wound healing were expected, we investigated responses to algal extract treatments applied during mid-dark (MD) and mid-light (ML) phases, finding that untreated cells healed faster in ML. These findings provide preliminary insights into the light-dependent effects of microalgal extracts and their potential application in aquaculture wound treatments.