# Plasticity of sex-biased aggression in response to the sex of territory intruders in an African cichlid fish, Julidochromis marlieri

## TL;DR

This study explores how an African cichlid fish adjusts aggressive behavior based on the sex of intruders and the sex of the larger partner in a pair.

## Contribution

The study reveals sex-specific aggression plasticity in response to intruder sex in a biparental cichlid species.

## Key findings

- Males respond more aggressively to male intruders when they are the larger partner in a pair.
- Females do not alter their aggression regardless of intruder sex when they are the larger partner.
- Aggression patterns are linked to the natural history and pair dynamics of the species.

## Abstract

Conspecific intruders represent unique threats to each sex in an established mating pair, where each member may respond differently to the intruder. We investigated how individuals from established pairs of
Julidochromis marlieri
, a biparental cichlid that forms female-larger pairs , respond to conspecific intruders of either sex. When males were the larger individual in the pair, they have increased responses to male intruders compared to female intruders; whereas when females were the larger individual, they did not change their behavior. We suggest the pressures on both sexes are different based on the natural history of the species.