Cleaner wrasse demonstrate mammal-like self-awareness through rapid mirror self-recognition and contingency testing behaviors

Osaka Metropolitan University research reveals cleaner wrasse exhibit rapid mirror self-recognition and contingency testing, traits usually linked to mammals, suggesting broader animal self-awareness.

By: AXL Media

Published: Feb 23, 2026, 5:58 AM EST

Source: The information in this article was sourced from EurekAlert!

Reversed marking procedure accelerates self-recognition

In standard mirror self-recognition tests, animals habituate to mirrors over days before receiving a mark, but this study inverted the sequence by applying visible marks resembling parasites first, then introducing the mirror. Cleaner wrasse responded almost immediately, with scraping behavior appearing in an average of 82 minutes, far quicker than the multi-day timelines in prior research. According to Shumpei Sogawa, specially appointed researcher, the fish sensed an unusual bodily condition but lacked direct sight of it, so the sudden mirror provided matching visual confirmation that triggered rapid action.

Contingency testing reveals sophisticated mirror understanding

After extended mirror exposure, some wrasse picked up small shrimp pieces from the tank floor, carried them upward, and dropped them deliberately near the mirror surface. As the shrimp sank, the fish tracked its reflection closely, repeatedly touching the glass with their mouths while observing the mirrored descent. This behavior demonstrates contingency testing, where the animal experiments with how external objects interact in reflected space, a cognitive trait previously documented in mammals like dolphins and certain marine species such as manta rays.

Flexible cognition beyond simple association

The researchers interpret these actions as evidence of higher-level, self-referential processing rather than rote learning or confusion with reflections. The deliberate manipulation of objects in relation to the mirror suggests the fish possess an understanding of the mirror as a tool for indirect observation. This builds on the group's earlier work showing cleaner wrasse can recognize themselves in photographs, further supporting their capacity for complex visual self-representation.