Thermal tolerance in an extremophile fish from Mexico is not affected by environmental hypoxia.

The thermal ecology of ectotherm animals has gained considerable attention in the face of human-induced climate change. Particularly in aquatic species, the experimental assessment of critical thermal limits (CTmin and CTmax) may help to predict possible effects of global warming on habitat suitability and ultimately species survival. Here we present data on the thermal limits of two endemic and endangered extremophile fish species, inhabiting a geothermally heated and sulfur-rich spring system in southern Mexico: The sulfur molly (Poecilia sulphuraria) and the widemouth gambusia (Gambusia eurystoma).

Multispecies collective waving behaviour in fish.

Collective behaviour is widely accepted to provide a variety of antipredator benefits. Acting collectively requires not only strong coordination among group members, but also the integration of among-individual phenotypic variation. Therefore, groups composed of more than one species offer a unique opportunity to look into the evolution of both mechanistic and functional aspects of collective behaviour.

Live fish learn to anticipate the movement of a fish-like robot.

The ability of an individual to predict the outcome of the actions of others and to change their own behavior adaptively is called anticipation. There are many examples from mammalian species-including humans-that show anticipatory abilities in a social context, however, it is not clear to what extent fishes can anticipate the actions of their interaction partners or what the underlying mechanisms are for that anticipation. To answer these questions, we let live guppies () interact repeatedly with an open-loop (noninteractive) biomimetic robot that has previously been shown to be an accepted conspecific.

Acoustic and visual stimuli combined promote stronger responses to aerial predation in fish.

Bird predation poses a strong selection pressure on fish. Since birds must enter the water to catch fish, a combination of visual and mechano-acoustic cues (multimodal) characterize an immediate attack, while single cues (unimodal) may represent less dangerous disturbances. We investigated whether fish could use this information to distinguish between non-threatening and dangerous events and adjust their antipredator response to the perceived level of risk.

Fish waves as emergent collective antipredator behavior.

The collective behavior of animals has attracted considerable attention in recent years, with many studies exploring how local interactions between individuals can give rise to global group properties. The functional aspects of collective behavior are less well studied, especially in the field, and relatively few studies have investigated the adaptive benefits of collective behavior in situations where prey are attacked by predators. This paucity of studies is unsurprising because predator-prey interactions in the field are difficult to observe.

Guppies Prefer to Follow Large (Robot) Leaders Irrespective of Own Size.

Body size is often assumed to determine how successfully an individual can lead others with larger individuals being better leaders than smaller ones. But even if larger individuals are more readily followed, body size often correlates with specific behavioral patterns and it is thus unclear whether larger individuals are more often followed than smaller ones because of their size or because they behave in a certain way. To control for behavioral differences among differentially-sized leaders, we used biomimetic robotic fish (Robofish) of different sizes.

An interaction mechanism for the maintenance of fission-fusion dynamics under different individual densities.

Animals often show high consistency in their social organisation despite facing changing environmental conditions. Especially in shoaling fish, fission-fusion dynamics that describe for which periods individuals are solitary or social have been found to remain unaltered even when density changed. This compensatory ability is assumed to be an adaptation towards constant predation pressure, but the mechanism through which individuals can actively compensate for density changes is yet unknown.

Using a robotic fish to investigate individual differences in social responsiveness in the guppy.

Responding towards the actions of others is one of the most important behavioural traits whenever animals of the same species interact. Mutual influences among interacting individuals may modulate the social responsiveness seen and thus make it often difficult to study the level and individual variation in responsiveness. Here, open-loop biomimetic robots that provide standardized, non-interactive social cues can be a useful tool.

Insights into the Social Behavior of Surface and Cave-Dwelling Fish () in Light and Darkness through the Use of a Biomimetic Robot.

Biomimetic robots (BRs) are becoming more common in behavioral research and, if they are accepted as conspecifics, allow for new forms of experimental manipulations of social interactions. Nevertheless, it is often not clear which cues emanating from a BR are actually used as communicative signals and how species or populations with different sensory makeups react to specific types of BRs. We herein present results from experiments using two populations of livebearing fishes that differ in their sensory capabilities.

On the occurrence of three non-native cichlid species including the first record of a feral population of () (Boulenger, 1899) in Europe.

Thermally influenced freshwater systems provide suitable conditions for non-native species of tropical and subtropical origin to survive and form proliferating populations beyond their native ranges. In Germany, non-native convict cichlids () and tilapia ( sp.) have established populations in the Gillbach, a small stream that receives warm water discharge from a local power plant.