Cleaning symbiosis between fishes is an interspecific interaction in which a fish (the cleaner) seeks food on the body surface of other fishes (the clients) which, in turn, become free of parasites and debris (Côté 2000). About 110 reef fish species in 21 families are known as cleaners (Côté 2000), and no doubt this figure will increase with additional field studies.

Here, we report for the first time cleaning by a triplefin blenny (Tripterygiidae) in the Tropical Eastern Pacific. An endemic to Malpelo Island, the twin-spot triplefin, Lepidonetes bimaculatus was observed cleaning the starry grouper, Epinephelus labriformis (Fig. 1) in August 2009 and February 2010. The cleaning interactions (n = 10) were always initiated by the cleaner, which moved slowly towards and climbed on the client, which posed almost motionless on the reef. The snout and dorsal fin of the clients were the most inspected body parts, at which the blenny occasionally pounced. All interactions lasted 1–2 min.

Fig. 1
figure 1

The triplefin blenny Lepidonetes bimaculatus (~5 cm total length) inspects the snout of the grouper Epinephelus labriformis, which poses on a rocky reef at 12-m depth at Malpelo Island, off Colombia

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Species of Tripterygiidae feed mostly on small benthic invertebrates (Feary et al. 2009), but three species from coastal New Zealand (temperate South Western Pacific) were observed cleaning: Notoclinops segmentatus, N. caerulepunctus, and Forsterygion lapillum (Clements 2003).