Peaceful by temperament, busy by nature
Zebra danios do not hunt, bully or claim territory, and in that sense they are honestly peaceful community fish. The complication is energy. A danio school spends the day in fast circuits of the upper water, darting at food and at each other in brief chases that end as quickly as they start. Calm species read that traffic as harassment even when no harm is meant, and slow fish simply lose every race to the food. So the right question is not whether danios are peaceful but whether the rest of your community lives at danio speed. Stocked with companions that share their pace and level of the tank, the school reads as cheerful background motion rather than a problem anyone has to manage.
Tankmates that work, and ones that do not
Good neighbours are other quick, robust fish of similar size that feed confidently — many rasboras, white cloud mountain minnows in cooler water, and unflappable bottom dwellers such as corydoras that work a different level of the tank entirely. The pairings to avoid are just as specific: bettas and guppies with flowing fins invite persistent nipping curiosity, angelfish are outpaced at feeding and stressed by the commotion while young, and shy, slow feeders can quietly thin in a danio tank while the school looks fat. School size is the other lever — in a group of eight or more, danios direct their chasing at each other and largely ignore everyone else, while a pair or trio exports that restless energy onto the rest of the community.
Setting up the tank so peace holds
Give the school a long swimming lane along the front and top, then break the rest of the space with plants and wood so slower residents have somewhere genuinely out of the traffic. Feed in two places at once, scattering a little at the far end for shyer fish while the school mobbing the first pinch is distracted, and consider sinking food after lights dim for bottom feeders. Introduce danios to an established community in full school numbers rather than singly, and quarantine new arrivals first so the peace you are protecting is not undone by disease carried in with the newest bag. Add them with the lights low and the residents freshly fed, which blunts the first hour of curiosity chases. A lid matters here too: community tanks get opened often, and a startled danio heading upward at speed will find any gap you leave.
When community friction needs a rethink
Occasional chasing inside the school is normal danio life and needs no intervention. Step in when the pattern changes its target: one fish relentlessly pursued and hiding, fins on a tankmate showing fresh nips day after day, or a companion that has stopped coming out to feed. First answers are usually structural — enlarge the school, add cover, split the feeding points — before anyone is rehomed. If a fish is injured or stops eating altogether, separate it and seek advice from an aquatic vet. Talking the stocking through with a shop listed in KinsLe through the Pet Services Directory is far cheaper than untangling a mismatched community later.