“…The relationship between glochidia and fish is mainly described as phoretic (i.e., a form of symbiosis where the symbiont is mechanically transported by its host) rather than nutritive or for protection. Glochidia usually do not grow while on the hosts (but see Barnhart et al., ; Douda, ; Fritts, Fritts, Carleton, & Bringolf, ; Reis, Collares‐Pereira, & Araujo, ; Taeubert et al., ), and they have a small (although detectable) impact on fish fitness and behaviour, which may increase at high levels of infestation and when mussels have longer encystment periods (as those of margaritiferid and quadruline species) (Horký, Douda, Maciak, Závorka, & Slavík, ; Slavík et al., ; Thomas, Adamo, & Moore, ). The main advantage of having fish as hosts is thought to be related to dispersal, including upstream colonization (Barnhart et al., ; Horký et al., ; Schwalb, Morris, & Cottenie, ; Schwalb, Poos, & Ackerman, ; Terui et al., ) and promoting connectivity among populations (Leibold et al., ; Newton, Woolnough, & Strayer, ).…”