Guppies are peaceful in the way a community tank needs: they hold no territory, pick on nobody, and spend their social energy on each other in flurries of display that end in chasing for a few seconds and never in injury. A guppy will share a tank with anything that does not eat it or shred it — and that second clause is the whole art of the guppy community, because the flowing tail that makes the male so handsome is, to a certain kind of fish, an invitation.
Peace inside the group: males, females, and ratios
The only friction in a guppy tank is romantic. Males court constantly, and a lone female paired with one male gets harassed to exhaustion; two or three females per male spreads the attention so everyone eats and rests. All-male groups work too, with theatrical flaring and circling that looks like fighting and almost never is — spread six or more males out so no single fish becomes the group's project. What keeps the peace, in both arrangements, is numbers and plants: enough guppies that attention diffuses, and enough cover that a fish wanting out of the spotlight can take it.
The fin-nipping problem
Tiger barbs are the textbook offender — a small school will reduce a male guppy's tail to ribbons in a week — but they are not alone: serpae tetras, black skirts, and nippy danios can all treat a drifting tail as a toy. Bettas are a coin flip in both directions, since a betta reads a fancy male guppy as a rival with a tail like his own. A torn tail is not just cosmetic: ragged fins invite infection, and the stressed fish at the surface is a guppy whose tankmates were chosen by looks instead of temperament.
Neighbors that suit them
Build the community from fish with the same manners. Platies and endlers share the guppies' water and temperament — note that endlers and guppies interbreed freely, which matters only if you care about keeping strains pure. Corydoras and otos work the bottom without a thought for anyone, small rasboras keep to mid-water peacefully, and snails are invisible to guppies entirely. Cherry shrimp adults coexist well, though guppies will snack on newborn shrimplets they find in the open; dense moss decides how many survive, and in most tanks the shrimp colony holds its own.
Keeping the peace as the tank matures
Stock the group at six or more, keep the surface planted enough to break sightlines, and watch tails at feeding time — fins are the tank's newspaper. A clean bite arc missing from a tail means a nipper has revealed itself and needs rehoming, while gradual fraying with white edges points to water or infection and a water test first. Peaceful fish do not need managing so much as they need the keeper to stop introducing exceptions; get the neighborhood right once, and a guppy community runs itself for years.
Sourcing those good neighbors is easier with local knowledge than with a lucky guess at a chain store's labels. Independent shops that know their stock can point you to genuinely gentle species, and KinsLe's Pet Services Directory helps you find trusted local pet businesses and connect with the ones other keepers rely on.