Client reef fish prefer more blue-saturated cleaner wrasses Labroides dimidiatus

Area of Science:

• Marine biology
• Animal behaviour
• Colour signalling

Background:

• Vivid colours in interspecific signalling aid species recognition and signal detection.
• Colour can indicate individual fitness, benefiting signal receivers.
• In cleaner wrasse-client mutualism, cleaner colour may signal service quality.

Purpose of the Study:

• To investigate if client fish perceive differences in cleaner wrasse blue colour saturation.
• To determine if clients use colour saturation to choose cleaners.

Main Methods:

• Threadfin butterflyfish (clients) were exposed to video sequences of cleaner wrasse with varying blue colour saturation (minimum, control, maximum).
• Client preference was measured by time spent in preference areas, frequency of facing, and entry rates near different saturation levels.

Main Results:

• Clients actively preferred video sequences of more saturated cleaners over less saturated ones.
• Preference was shown through increased time in areas, more frequent and longer facing durations, and higher entry rates near brighter blue cleaners.

Conclusions:

• Cleaner wrasse blue colour saturation is perceived by clients.
• Colour saturation likely serves as a signal of individual quality, influencing client choice in cleaner fish selection.
• This visual cue aids clients in selecting cleaners that provide superior service.