Fishes associating with shallow water echinoids at Roatán, Honduras

We studied the association of 11 species of fishes with 5 species of echinoids at Roatan, Honduras, from 27 August to 1 September 2017. Fishes associated most frequently with the echinoid Diadema antillarum (34.3% of echinoids, six fish species, n = 146 echinoids), followed by Echinometra viridis (25.0%, three fish species, n = 12), Echinometra lucunter (7.5%, ten fish species, n = 1,834), Eucidaris tribuloides (3.4%, four fish species, n = 116), and Tripneustes ventricosus (7.1%, one fish species, n = 28). Of 196 fishes seeking shelter beside echinoids, Malacoctenus aurolineatus was the most common (41.8% of fishes, three echinoid species), followed by Stegastes adustus (38.8%, three echinoid species), Stegastes diencaeus (6.6%, three echinoid species), Sargocentron coruscum (6.1%, five echinoid species), Chaetodon capistratus (1.5%, one echinoid species), Gobioclinus filamentosus (1.5%, one echinoid species), Pomacanthus paru (1.0%, two echinoid species), Labrisomus nuchipinnis (1.0%, two echinoid species), Equetus punctatus (0.5%, one echinoid species), Microspathodon chryurus (0.5%, one echinoid species), and Thalassoma bifasciatum (0.5%, one echinoid species). None of the fishes associated exclusively with echinoids or was specialized for associating with echinoids, indicating the association was facultative. All fishes were small (< 12 cm). Fishes associated most frequently with the longest-spined echinoid, D. antillarum, supporting the hypothesis that fishes seek shelter among the spines of echinoids to benefit from increased protection from predation.