Short-sword platyfish
Xiphophorus continens
Short-sword platyfish exhibit a vibrant coloration with a distinctive sword-like tail and a small, laterally compressed body.
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About the Short-sword platyfish
Xiphophorus continens is a tiny little wild-type livebearer from the Rio Panuco drainage in Mexico, and the males have just a short "stub" sword instead of the big flowing one you see on common swordtails. They really shine in a planted, oxygen-rich tank with some current, where you can watch the males do their low-key "sneaker" style mating behavior and the females quietly cruise the plants.
Also known as
Quick Facts
Size
3.5 cm
Temperament
Peaceful
Difficulty
Intermediate
Min Tank Size
10 gallons
Lifespan
3-5 years
Origin
Central America (Mexico - Rio Panuco basin)
Diet
Omnivore - small flakes/micro pellets, frozen foods (daphnia, cyclops, baby brine), and biofilm/algae grazing
Water Parameters
20-25°C
7-8
8-20 dGH
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This species needs 20-25°C in a 10 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Give them a longer tank over a tall one - they cruise midwater and appreciate open swimming space with some plants to duck into (Java moss, guppy grass, hornwort).
- They do best in hard, alkaline water: aim around pH 7.2-8.2 and moderately hard to hard GH; they get finicky and prone to issues in soft, acidic setups.
- Keep temps in the low-to-mid 70s F (around 72-78F) and dont cook them long-term in the 80s or they burn out faster and males stay extra pushy.
- Feed small amounts 1-2 times a day and mix it up: a decent flake or micro pellet plus green stuff (spirulina, blanched zucchini, algae wafers) keeps their guts happy.
- They are generally chill community fish with other peaceful livebearers, small tetras, Corydoras, and shrimp that have hiding spots; skip fin-nippers (some barbs) and anything that will harass or eat fry.
- Males will pester females nonstop, so keep them in groups with more females than males (think 2-3 females per male) or youll see stressed, beat-up females.
- They will drop fry regularly if both sexes are present, and the adults will snack on babies - dense floating plants or a clump of moss saves way more fry than a bare tank.
- Watch for livebearer classics: shimmying and clamped fins often show up when the water is too soft or swings around; if you see stringy poop, back off feeding and add more veg/fiber for a few days.
Compatibility
Good Tankmates
- Small, chill tetras (ember tetras, neon tetras) - they stay in their lane, and the short-sword platies just cruise around and ignore them
- Corydoras catfish - perfect bottom crew, totally peaceful, and the platies never bother them (just make sure the corys have sand or smooth gravel)
- Small rasboras (harlequin rasboras, chili rasboras) - calm midwater swimmers that match the platy vibe and do great in a planted community tank
- Otocinclus - great little algae pickers that dont mess with anyone; the platies will mostly act like they dont exist
- Peaceful dwarf shrimp like Amano shrimp (and usually larger Neocaridina colonies in a planted tank) - platies are not hardcore predators, but they will absolutely grab tiny baby shrimp if they can
- Honey gourami - generally mellow centerpiece fish, and they wont outcompete or bully short-sword platies in a normal community setup
Avoid
- Fin-nippers like tiger barbs - they get bored and start picking, and platies are easy targets when that happens
- Aggressive or territorial stuff like cichlids (convicts, most mbuna, even spicy dwarfs in a small tank) - platies are peaceful and get stressed and chased
- Bettas (especially male bettas) - sometimes it works, but a lot of bettas see platies as flashy invaders and either chase them or get stressed by the constant platy movement
Where they come from
Short-sword platies (Xiphophorus continens) come from Mexico, where they live in smaller streams and spring-fed waters. Think clear-ish water, steady flow in spots, lots of plants and edge cover, and a mix of sun and shade. They are close cousins to the common platy, but they tend to feel a little more "wild-type" in behavior and sensitivity.
If you have only kept store-bred platies, these can feel a bit more particular. Once they settle, they are hardy enough, but they do not love big swings in temperature or water quality.
Setting up their tank
Give them a planted tank with broken sightlines and gentle flow. They are small, active fish, and they look best when they can weave through stems and hover around cover instead of being stuck in an empty box.
- Tank size: 15-20 gallons works great for a small group. You can do smaller, but stability gets harder.
- Temperature: 72-78 F. I keep mine around 74-76 F and they act calm and eat well.
- pH and hardness: neutral to alkaline and moderately hard is usually easiest. They do fine in typical "livebearer" water.
- Filtration: sponge filter or a gentle HOB. Aim for clean water, not a washing machine.
- Decor: lots of live plants (guppy grass, hornwort, java moss, water sprite), plus some rock/wood for cover.
- Substrate: anything works, but darker substrate makes their colors pop and they act less jumpy.
They jump more than people expect. A simple lid saves you from the classic "where did that fish go" moment.
I like to start them in a mature tank. Fresh setups with that "new tank" wobble can stress them out, and stressed livebearers are magnets for fin nips, fungus, and random losses.
What to feed them
These are easy eaters once they are comfortable. They graze in the tank and will pick at biofilm and soft algae, but they still need real meals.
- Staple: a good quality flake or small pellet for livebearers, crushed to match their mouth size
- Greens: spirulina flake, blanched zucchini, or a little repashy-style gel food with plant matter
- Protein treats: baby brine shrimp, daphnia, cyclops, and the occasional bloodworm (not as a daily food)
- Fry food: powdered fry food, crushed flake, and baby brine shrimp if you want fast growth
If you see stringy poop or they look "pinched" behind the head, back off the rich foods for a bit and feed more spirulina and daphnia. Livebearers get backed up pretty easily.
How they behave and who they get along with
They are generally peaceful, but like most livebearers the males stay busy. You will see chasing, posturing, and nonstop "dating." In a cramped tank, that turns into stress fast.
- Group size: keep them in groups, not pairs. A small colony spreads out attention and looks more natural.
- Male to female ratio: shoot for 1 male to 2-3 females, or go all-male if you do not want fry.
- Good tankmates: other calm community fish that like similar water (small tetras, rasboras, peaceful rainbowfish in larger tanks), plus shrimp and snails if your fish are well fed
- Avoid: aggressive fin nippers, big fast feeders, and anything that bullies smaller livebearers (some barbs, large gouramis, larger cichlids)
They also do better with visual cover. If the tank is open and bright, they tend to hug corners. Add plants and they start using the whole tank.
Breeding tips
Yep, they are livebearers. If you keep males and females together, you will get fry. Not always right away, but it will happen.
- If you want fry to survive: pack the tank with moss and fine plants. Guppy grass is basically a fry daycare.
- Skip most breeder boxes: they stress females out. I have better luck letting them drop in a planted tank.
- Feed small and often: 2-3 light meals a day grows fry faster than one big dump of food.
- Cull with kindness: if you are line-breeding or trying to keep numbers sane, plan ahead for where extra fish will go.
Females can store sperm. You can separate sexes and still see fry for a while.
Common problems to watch for
Most issues I see with this species come from the usual livebearer combo: stress, overcrowding, and water that is not getting enough maintenance.
- Shimmies: often shows up when they are chilled, stressed, or not happy with mineral balance. Warm the tank a bit, keep water changes steady, and avoid sudden swings.
- Ich and velvet: they can get hit after a stressful move. Quarantine new fish if you can, and do not rush acclimation.
- Fin nipping: usually a stocking/space issue or the wrong tankmates. More plants and a better male to female ratio helps a lot.
- Bloat/constipation: too much rich food and not enough roughage. Add spirulina and daphnia, and do smaller feedings.
- Fry disappearing: normal. Adults will snack on fry unless the tank is heavily planted.
If they act "skittish for no reason," check nitrate and overall cleanliness first. With these, behavior is often your early warning system.
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