How big do platies get?
5–7 cm (2–3 inches) at adulthood — small fish that stay small, which is why they are so often overstocked.
How long do platies live?
3–5 years in clean, heated water. Cold, unfiltered "starter" tanks are the usual reason platies die inside a year.
Platy tank size and water parameters
A small group wants 40+ liters (10+ gallons), heated to 22–26 °C, pH 7.0–8.2. Hardy, but "hardy" still means cycled, warmed and filtered.
What do platies eat?
Omnivores: a quality flake or micro pellet base plus regular plant matter (blanched zucchini, peas, spinach) and occasional live or frozen food such as brine shrimp or daphnia. They graze algae but cannot live on algae alone.
Platy tank mates
Good: guppies, mollies, corydoras, neon tetras and peaceful rasboras. Avoid: large or aggressive fish, and persistent fin-nippers.
How to tell if a platy is pregnant — and what to do
A gravid (pregnant) female develops a dark gravid spot near the rear and her belly becomes noticeably squared off. Gestation is about 24–30 days, and she delivers 20–40 live fry. Dense plants (hornwort, guppy grass) or a breeder box are what stand between the fry and the adults.
Beginner mistakes to avoid
- Overstocking because platies are small — a dozen platies in a 40-liter tank is a water-quality disaster.
- No plants, then wondering where all the fry went.
- Keeping platies with tiger barbs or other fin-nippers.
- Wrong sex ratio: one male chasing several females stresses the females; aim for one male per two to three females.