Black Swordtail tank mates
Xiphophorus hellerii
5 rated pairings from the Black Swordtail care guide. Compatibility here means water, temperament, tank zone and adult size all line up — the note on each card says why. Black Swordtail needs at least 20 gallons on its own; every companion adds to that.
Excellent matches
3 · Same water, complementary zones, no conflict.
Guppy
Poecilia reticulata
10 gal min · 2" adult · Peaceful
Similar size, peaceful temperament, and identical water parameter requirements make them ideal companions
Platy
Xiphophorus maculatus
10 gal min · 2.5" adult · Peaceful
Fellow livebearers with matching water needs and peaceful behavior; compatible in community settings
Gold Mystery Snail
Pomacea bridgesii
5 gal min · 2" adult · Peaceful
Algae grazer that occupies different ecological niche; prefers hard water like swordtails
Good matches
2 · Compatible with normal care — watch space and numbers.
Harlequin Rasbora
Trigonostigma heteromorpha
10 gal min · 2" adult · Peaceful
Peaceful schooling fish that thrives in slightly alkaline water; minimal competition for resources
Bristlenose Pleco
Ancistrus sp.
20 gal min · 5" adult · Peaceful
Nocturnal algae eater that helps maintain tank cleanliness without competing for food or space
Planning this tank?
Run the whole stock list through the calculator — it checks bioload and schooling numbers, not just pairings.