Variable platyfish

Where they come from

Variable platies are from eastern Mexico, in slow-moving creeks and ditches with lots of plants and hard, alkaline water. They handle cooler water better than a lot of other livebearers, which is why they do well in many room-temperature homes.

Setting up their tank

I like a 20-gallon long for a small group. You can run a trio in a 10, but behavior and water quality are easier in a 20. Add a lid; platies can and will hop during chasing or water changes.

• Tank size: 20 gal for a group is comfy
• Temperature: 68-75 F (20-24 C). Short trips to 77 F are fine, but they do not need it hot
• pH: 7.2-8.2
• Hardness: GH 10-20+ dGH, KH 6-12 dKH (they like minerals)
• Filtration: sponge or HOB with gentle-moderate flow; add a pre-filter sponge to save fry
• Aquascape: sand or fine gravel, lots of plants (vallisneria, hornwort, water sprite, floating plants), open swimming space in the middle
• Lighting: moderate; some algae growth is normal and they will graze it

Keep the tank stable and clean. I do 30-50% water changes weekly, vacuum lightly, and keep nitrates under 20-30 ppm. They are hardy, but new tanks with swinging parameters can still knock them around.

• Cycle the tank before adding fish
• Aim for 0 ammonia, 0 nitrite, nitrate under 20-30 ppm
• Add floating plants for cover and to soak up nutrients

What to feed them

They are constant nibblers and do best with a veggie-heavy diet. Think quality flake or small pellets as the base, with greens and some live or frozen foods for variety.

• Staple: high-quality flake or micro-pellets with spirulina or other plant matter
• Veggies: blanched zucchini, spinach, or peas (skinned) now and then
• Treats: frozen or live baby brine shrimp, daphnia, cyclops
• Algae wafers or spirulina flakes for extra fiber

How they behave and who they get along with

Friendly, busy, and always on the go. Males will chase, so keep 1 male to 2-3 females or run an all-female group if you do not want babies. In bigger tanks, groups of 6+ spread out the attention nicely.

• Great tankmates: peaceful tetras (ember, neon in cooler rooms), rasboras, white cloud mountain minnows, corydoras, otos, snails
• Usually fine with peaceful gouramis and other livebearers that like similar water
• Shrimp: adults might be OK, but tiny shrimplets will get picked off

Match tankmates that enjoy the same cooler end of tropical water. If the rest of your fish want 80 F+, pick something other than variatus.

Breeding tips

They are classic livebearers. Females drop fry every 4-6 weeks once mature. A single female can store sperm and have multiple batches without a male around. Typical drops are 10-50 fry, sometimes more as the female gets larger.

• If you want lots of fry: add thick plants (water sprite, guppy grass), keep a gentle filter, and offer baby brine shrimp or powdered fry food
• Net breeders work in a pinch, but dense plants are less stressful
• Do not overheat the tank; steady 72-74 F has given me strong, well-developed fry

Common problems to watch for

• Soft-water shimmying: wobbling or tail-shaking without moving. Usually a mineral issue. Add calcium/magnesium via crushed coral or a remineralizer.
• Ich after chilly drafts or big temp swings: add a lid, keep temps steady, and quarantine newcomers.
• Camallanus worms: red threads from the vent. Quarantine new fish; treat promptly if you see it.
• Fin rot or ragged fins: usually water quality or nipping. Clean up the schedule and check tankmates.
• Bloat/constipation: too much rich food. Add more greens, feed lighter, and consider a fast day.
• Population booms: they breed well. Plan for it or keep single-sex groups.