A social cichlid fish failed to pass the mark test

Area of Science:

• Ethology
• Comparative Psychology
• Animal Cognition

Background:

• Mirror self-recognition (MSR) is the ability to recognize oneself in a mirror, typically assessed using the mark test.
• MSR has been documented in various species, including great apes, elephants, dolphins, and some birds, often associated with high sociality.
• MSR in fish remains largely unexplored, despite their complex social structures.

Purpose of the Study:

• To investigate mirror self-recognition (MSR) in the highly social Tanganyikan cichlid, Neolamprologus pulcher.
• To determine if N. pulcher exhibits self-recognition behaviors when presented with a mirror image.
• To assess the applicability of the mark test in evaluating MSR in fish.

Main Methods:

• N. pulcher were exposed to a mirror, and their behavioral responses were recorded.
• The mark test was administered by applying an imperceptible mark to the fish.
• Subsequent behaviors, including scraping and observation of the marked area, were analyzed to assess contingency checking.

Main Results:

• Initially, N. pulcher displayed aggressive behaviors towards their mirror image, interpreting it as an unfamiliar conspecific.
• These social responses diminished over time, a pattern observed in species with MSR.
• However, fish did not increase scraping or observation of the marked area after mark injection, indicating a failure to pass the mark test.

Conclusions:

• Neolamprologus pulcher failed to demonstrate mirror self-recognition (MSR) in the mark test.
• The study suggests that MSR may not be exclusively linked to high sociality, as previously hypothesized.
• Further research is needed to understand the evolution and distribution of MSR across diverse taxa.