Skunk cleaner shrimp inspects the mouth of a complying anthias. Photo by Scott W. Michael.
We aquarists have long suggested that cleaner shrimps will remove cysts from fishes infected with Cryptocaryon irritans and may also ingest other parasites (e.g., trematode flatworms). Well, it turns out that science supports our anecdotal observations. Let's take a look at the scientific evidence. The first study of interest was conducted by Williams and Williams (1998) - they documented that Pederson's anemone shrimp (Periclimenes pedersoni) feeds on the larvae of parasitic isopods. Even more exciting was a study done by Becker and Grutter (2004). They analyzed cleaner shrimp gut contents as well as conducted some aquarium studies. They found that wild cleaner shrimps in the genus Urocaridella and Ancylomenes (formerly Periclimenes) holthuisi (known commonly as Holthuis' anemone shrimp) fed on parasitic crustaceans (e.g., isopods, copepods) and monogenean flatworms (Benedenia sp.). They also demonstrated that captive A. holthuisi reduced the parasitic load (in this case flatworms) by 74 % on captive surgeonfish. In the most recent study, Militz and Hutson (2015) documented that captive -held skunk cleaner shrimp (Lysmata amboinensis) will reduce infestations of a trematode in the genus Neobenedenia in groups of lyretail anthias (Pseudanthias squamipinnis). The shrimp reduced the infection success by the trematodes by half compared to controls that were not housed with shrimp. These beneficial crustaceans were found to eat both the flatworm's eggs and the larvae.
