Androgens and corticosteroids increase in response to mirror images and interacting conspecifics in males of the Siamese fighting fish Betta splendens

Andreia Ramos; Deepa Alex; Sara D Cardoso; David Gonçalves

doi:10.1016/j.yhbeh.2021.104991

Androgens and corticosteroids increase in response to mirror images and interacting conspecifics in males of the Siamese fighting fish Betta splendens

Horm Behav. 2021 Jun:132:104991. doi: 10.1016/j.yhbeh.2021.104991. Epub 2021 May 10.

Authors

Andreia Ramos¹, Deepa Alex², Sara D Cardoso³, David Gonçalves⁴

Affiliations

¹ Institute of Science and Environment, University of Saint Joseph, Macao. Electronic address: andreia.ramos@usj.edu.mo.
² Institute of Science and Environment, University of Saint Joseph, Macao. Electronic address: deepa.mora@usj.edu.mo.
³ Institute of Science and Environment, University of Saint Joseph, Macao. Electronic address: sara.cardoso@usj.edu.mo.
⁴ Institute of Science and Environment, University of Saint Joseph, Macao. Electronic address: david.goncalves@usj.edu.mo.

PMID: 33984609
DOI: 10.1016/j.yhbeh.2021.104991

Abstract

The role of hormones as modulators of aggressive behavior in fish remains poorly understood. Androgens and corticosteroids, in particular, have been associated with aggressive behavior in fish but it is still not clear if animals adjust the secretion of these hormones to regulate behavior during ongoing fights, in response to fight outcomes in order to adjust aggressive behavior in subsequent fights, or both. With its stereotyped displays and high aggression levels, the Siamese fighting fish Betta splendens is an excellent model to investigate this question. Here, we compared the behavioral and endocrine response of male B. splendens to fights where there is no winner or loser by presenting them with a size-matched live interacting conspecific behind a transparent partition or with a mirror image. The aggressive response started with threat displays that were overall similar in frequency and duration towards both types of stimuli. Fights transitioned to overt attacks and interacting with a live conspecific elicited a higher frequency of attempted bites and head hits, as compared with the mirror image. There was a pronounced increase in plasma androgens (11-ketotestosterone and testosterone) and corticosteroids (cortisol) levels in response to the aggression challenge, independent of stimulus type. Post-fight intra-group levels of these hormones did not correlate with measures of physical activity or aggressive behavior. A linear discriminant analysis including all behavioral and endocrine data was a poor classifier of fish from the conspecific and mirror trials, showing that overall the behavioral and endocrine response to mirror images and conspecifics was similar. The results show that fight resolution is not necessary to induce an evident increase in peripheral levels of androgens and corticosteroids in B. splendens. However, the function of these hormones during present and future aggressive contests remains to be clarified.

Keywords: Aggression; Androgens; Betta splendens; Corticosteroids; Live conspecific test; Mirror test.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adrenal Cortex Hormones
Androgens*
Animals
Fishes*
Male

Substances

Adrenal Cortex Hormones
Androgens