Three to five years of restless energy
A swordtail lives 3 to 5 years in a home aquarium. It is the largest and most athletic of the common livebearers — a male with a full sword can approach five inches — and its lifespan reflects a life lived at higher revs than a platy's or a molly's. Swordtails are constantly in motion: males displaying, sparring and courting, the whole group patrolling the tank's length. That energy is the pleasure of keeping them, but it also means their years are spent faster and their keeping has one unforgiving rule that the calmer livebearers do not impose.
The lid is a lifespan device
Swordtails jump — accurately, powerfully, and through gaps you would swear were too small. A fish evolved to leap between connected waters treats the slot around a filter pipe or an open feeding hatch as an exit, and a swordtail on the floor is the most common premature end this species meets. A gapless cover, with cut-outs fitted tightly around equipment, is not an accessory for this fish; it is the difference between a five-year resident and a first-month loss. The same athleticism demands swimming room: length matters far more than depth, and a group cruising a long tank stays fitter, quarrels less and lives measurably better than one circling a tall, narrow column.
Males burn bright; manage the burn rate
The sword itself is part of the story. A dominant male spends his days in near-constant display and pursuit, and that expenditure, plus the stress absorbed by any single female he fixates on, shortens lives at both ends of the chase. The keeper's levers are ratios and geography: two or three females per male, dense planting and broken sightlines so a pursued fish can genuinely disappear, and enough length that a subordinate male can keep out of the dominant one's patrol route. Late-developing males — the ones that look female for months before a sword appears — are a normal quirk of this species, not a problem to solve. Feeding should match the activity level without indulging it: one solid daily meal with regular vegetable matter keeps swordtails in condition, while constant rich feeding produces heavy, short-lived fish.
Water, age and the signs worth acting on
Swordtails come from flowing Central American waters and do best in moderately hard, neutral to alkaline water around 72 to 79°F with a little movement in it — a filter outflow they can ride is genuinely used, not decoration. An ageing swordtail keeps its sword and its appetite long after it slows, so treat changes as signals rather than birthdays: a fish hanging at the surface, fins clamped, or a female gone suddenly thin after delivering fry all warrant a water test the same day. In a breeding group, nitrate from the fry production line creeps upward quietly, and generous regular water changes are the unglamorous habit behind most five-year swordtails.
Because the lid rule is exactly the sort of thing a holiday helper would never guess, KinsLe Care Pass hands your sitter the tank's routine in writing — feed this much, and never leave the cover open — so your swordtails are still in the water when you get home.