What If Gone

Species → Bluestreak Cleaner Wrasse

Bluestreak Cleaner Wrasse

Labroides dimidiatus

No global figure — a common species on Indo-Pacific coral reefs, with…
Extinction risk Least Concern
Obligate mutualismCoral reefKeystone speciesMarine environment
Bluestreak Cleaner Wrasse (Labroides dimidiatus)
Photo: Diego Delso, Wikimedia Commons (CC BY-SA 4.0)

What if it disappeared?

Impact High
In a single day

A single cleaner wrasse can perform more than 2,200 cleaning interactions a day, consuming more than 1,100 parasites — and a client fish's parasite load can increase 4.5-fold in just twelve hours when the cleaner is absent.

Documented
Detail

Grutter, A.S. (1999). Cleaner fish really do clean. Nature, 398, 672–673.

By tracking parasitic isopod (Gnathiidae) numbers on client fish over the course of a day, with and without access to the cleaner, the study provides the first direct evidence that cleaning genuinely reduces parasite load — rather than the cleaner simply feeding on mucus or healthy skin, as some had proposed.

8.5 years, Lizard Island

After 8.5 years with no cleaner wrasse at all, experimental reefs show 37% fewer resident fish, 23% fewer species, and 65% fewer newly recruited juveniles than comparable control reefs where the species is present.

Documented
Detail

Waldie, P.A., Blomberg, S.P., Cheney, K.L., Goldizen, A.W. et Grutter, A.S. (2011). Long-Term Effects of the Cleaner Fish Labroides dimidiatus on Coral Reef Fish Communities. PLoS ONE, 6(6), e21201.

This removal experiment, one of the longest ever conducted on a reef fish, extends over nearly a decade a study begun by Grutter and colleagues in 2003. Reefs without cleaners averaged 561 resident fish versus 891 on control reefs, 15.5 species versus 20.1, and 11.6 visiting juveniles versus 33.2 — the study also establishes, for the first time, that fish with access to cleaning grow to a larger size than those without.

Documentation

Last verified: August 14, 2026