Competitive cleaning: behavioural variation supports coexistence of two juvenile sympatric cleanerfishes

Cleanerfish support coral reef ecosystems by providing important services to client fishes. Cleanerfish species often coexist, but how interspecies dynamics influence cleaning networks across life-history stages remains largely unknown. Here, we investigated the effects of interspecific competition on the behaviour of two juvenile cleaner wrasses, Labroides dimidiatus and Labroides bicolor. Under competitive scenarios, L. dimidiatus exhibited higher levels of client association compared to L. bicolor, while no differences were observed under non-competitive conditions. These behavioural differences likely facilitate resource partitioning and coexistence, supporting the stability of coexisting mutualistic networks in coral reef ecosystems.