Environmental Biology of Fishes

, Volume 86, Issue 3, pp 427–441

Why is the neon tetra so bright? Coloration for mirror-image projection to confuse predators? “Mirror-image decoy” hypothesis

Article

DOI: 10.1007/s10641-009-9543-y

Cite this article as:
Ikeda, T. & Kohshima, S. Environ Biol Fish (2009) 86: 427. doi:10.1007/s10641-009-9543-y

Abstract

The neon tetra (Paracheirodon innesi), which inhabits blackwater streams of the Amazon basin, has extremely bright coloration characterized by metallic blue-green stripes. To clarify the ecological function of this coloration, we examined the appearance of living neon tetra. They changed color in response to lighting and background conditions, and became less conspicuous under each condition to the human eye. Although they appeared bright in colorless clear water, their stripes appeared darker in blackwater. In addition, the visible area of their stripes was small and their brightness decreased, unless they were observed within a limited viewing angle (approximately 30° above the horizon). The results show that from the viewpoint of approaching submerged predators, a bright mirror image of the stripes is projected onto the underside of the water’s surface, providing a dramatic visual target while the real fish remains less conspicuous. Based on these results, we hypothesize that the neon tetra’s bright coloration is an effective predator evasion strategy that confuses predators using bright mirror images.

Keywords

Anti-predationCamouflageIridophoreAposematic

Abbreviations

θ

the angle between the horizontal and the line of measurement/sight

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Graduate school of Bioscience and BiotechnologyTokyo Institute of TechnologyTokyoJapan
  2. 2.Wildlife Research CenterKyoto UniversityKyotoJapan