As shoaling creatures, social status is a big thing for zebra danios (Danio rerio). Shoaling fish are highly social and are usually seen swimming together in sizable groups. While zebra danios often thrive in community aquariums alongside serene specimens, aggressive behavior is not unheard of in the species.
Social Status and Aggression in Captivity
Power in the zebra danio world isn't generally determined by factors such as size and gender. Zebra danios sometimes behave fiercely when they're not in the company of many other fish. In an underpopulated tank, they'll often nip or chase after fish of lower ranking. When they have more company, they typically don't act as fiercely. If you own zebra danios, make sure their living environment isn't ever overly cramped or overly empty. The presence of too many fish is also a problem for zebra danios, as it can cause them to feel extremely frustrated and anxious.
Social Status and Aggression in the Wild
Dominant zebra danios in the wild often express their power by setting up individual turf close to mating grounds. When zebra danios have dominant status, others generally behave submissively to them, whether it comes to food or to territory. Zebra danios in nature generally breed in aquatic environments with silt on the floor. Like zebra danios in captivity, the wild guys gain dominant status through fierce behaviors such as chasing and nipping. Wild zebra danios also frequently express their power by taking over food access, sometimes leaving little to no sustenance for others of lower ranking.
Forms of Aggression
Biting and rapid following aren't the only forms of aggression that zebra danios are capable of exhibiting. They sometimes show off their aggressive sides by keeping their mouths ajar, elevating their fins and making conspicuous wavy motions with their physiques. A handful of motives can cause these threatening behavior, including protecting turf, guarding sustenance and showing social power. Breeding male specimens can be extremely protective of territory. They often persistently go after females.
Minimizing Fierceness in Zebra Danios
Aggressiveness in zebra danios often fades away once they've figured out their social ranking system. You can help to curb aggressive behavior, meanwhile, by making the tank environment more detailed. Ample hiding spots, like rocks, can be beneficial for minimizing fierceness. Fish often behave more calmly when they have many places to hide. Artificial grass made of plastic also can work well for hiding spots.
When selecting tankmates for zebra danios, opt for mild-mannered fish species that aren't bigger or smaller than them. Zebra danios flourish in social units of a minimum of three individuals. Outside of fellow zebra danios, they tend to do well with tetras, mollies, gouramis, barbs, plecos, loaches and rasboras, for starters. Try to avoid keeping zebra danios with fish with especially lengthy fins. Zebra danios sometimes feel compelled to bite conspicuous fins.
- University of Zurich Institute of Molecular Life Sciences: Towards a Comprehensive Catalog of Zebrafish Behavior 1.0 and Beyond
- Handbook of Laboratory Animal Management and Welfare; Sarah Wolfensohn and Maggie Lloyd
- Zebrafish; Christiane Nusslein-Volhard and Ralf Dahm
- Fish Physiology - Zebrafish; Steve F. Perry et al.
- University of Michigan Animal Diversity Web: Danio Rerio
- Stockbyte/Stockbyte/Getty Images