Males are quicker to adjust aggression towards heterospecific intruders in a cichlid fish

Aggression towards shared enemies by heterospecific and conspecific cichlid fish neighbours

“…In contrast, moga territories in the study area were defined by excavations that the fish had dug in the sediment (Lehtonen 2008). The ‘close’ distance (~ 50 cm) was chosen to correspond to a typical radius of a moga territory (Lehtonen 2008; Lehtonen et al 2015; Lehtonen and Wong 2017), as well as the low end of between-territory distances commonly observed in the wild (personal observations; see also Lehtonen et al 2018).…”

“…In experiment 3, I assessed the rate of aggression directed to an intruder model, which was placed next to the focal convict cichlid territory that was associated with a nesting resource (see above) and occupied by a convict cichlid pair. In particular, to have control over intruder approaches, I presented the focal convict pair with a ‘dummy’ model of a sympatric cichlid fish, Amphilophus sagittae (as per Lehtonen 2017; Lehtonen and Wong 2017; Fig. 1b).…”

“…Similarly, mogas have been found to be up to 50% more aggressive towards the gold than the dark colour morph (Lehtonen et al 2015). More generally, hand-made intruder models have been very useful for measuring rates of aggression in cichlids (Cravchik and Pazo 1990; Barlow and Siri 1994; Ochi and Awata 2009), including the convict cichlid (Beeching et al 1998; Anderson et al 2016) and moga (Lehtonen et al 2015; Lehtonen and Wong 2017). The intruder model used in the current study was made by glueing a waterproof, photographic colour print of the lateral side of an adult A .…”

“…sagittae (sex unknown) onto each lateral side of an elliptical floating plate (thickness: 6 mm). The model was 16 cm long and attached to a small sinker with a thin, transparent fishing line (following Lehtonen 2017; Lehtonen and Wong 2017), so that it floated in a natural position approximately 10 cm above the substratum (Fig. 1b).…”