Description
Poecilia velifera is the giant sailfin molly, a livebearer of up to 15 cm endemic to south-eastern Mexico. The adult male displays an enormous sail-shaped dorsal fin, which is what tells it apart at a glance from the common sailfin molly (Poecilia latipinna), another species. As juveniles they can be told apart only by counting the dorsal-fin rays, 18 or 19 in velifera against 14.
It is harder to keep than other mollies: it needs hard, alkaline, clean water, a large and uncrowded tank for the male to develop the sail, and it does not thrive in soft or acidic water. It does not need salt. It can be combined with other hard-water livebearers, but not with other mollies, with which it crosses.
Behavior
Peaceful in the community tank, always with fish that tolerate hard water. As with all livebearers, the males harass without respite: a trio of two females per male, dense and floating plants and open areas for swimming are advisable.
It lives well with other livebearers such as swordtails and platies (not with other mollies, with which it crosses), some gouramis, hardy corydoras and loricariids, and some barbs and tetras. Also in a brackish set-up with chromides and gobies.
Avoid housing it with soft, acidic water fish, which do not share its parameters, and with other mollies.
Habitat
Poecilia velifera is endemic to south-eastern Mexico: Yucatán, Quintana Roo and the lower Usumacinta to the Laguna de Términos. It lives in fresh and brackish water, and introduced populations have become established in several countries, among them Colombia, Israel, Singapore and Taiwan: an aquarium fish must never be released.
It feeds on worms, crustaceans, insects and plants. Its natural water is hard and alkaline, and that hardness (calcium and magnesium) is what it needs, not salt.
Details
🌊 Water parameters
🐠 Minimum tank size
Breeding
Relatively difficult compared with other livebearers. Gestation lasts four to eight weeks and up to two hundred young can be born, although twenty to sixty is usual. The fry are large at birth and accept brine shrimp nauplii, microworms or powdered flake from day one.
The breeding tank must be heavily planted if the young are to survive the parents and other fish. The safest course is to move the gravid female to another tank until she gives birth. Wild fish eat their young less than domestic forms do.
Diet
Omnivorous: in the wild it eats zoobenthos, worms, crustaceans, insects, plants and detritus. In the aquarium it accepts almost anything, live, frozen or dry, but it needs some greens.
- Staple: quality flakes with a plant component.
- Supplement: blanched spinach, cucumber and algae wafers, plus live or frozen food now and then.
What about your tank?
Enter your tank's values to see only the compatible species that fit them. Litres apply to fish.
Compatible fish
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7–7.5 and 22–27 °C.
They share water: pH 7–8 and 23–28 °C.
They share water: pH 7–8 and 22–26 °C.
They share water: pH 7–7.5 and 24–28 °C.
They share water: pH 7 and 23–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.8 and 22–25 °C.
They share water: pH 7–7.5 and 22–27 °C.
They share water: pH 7–7.5 and 24–28 °C.
They share water: pH 7 and 24–27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 24–26 °C.
They share water: pH 7–8 and 22–26 °C.
They share water: pH 7–7.5 and 24–28 °C.
They share water: pH 7–7.5 and 22–24 °C.
They share water: pH 7–7.5 and 24–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8.5 and 22–28 °C.
They share water: pH 7–8 and 22–27 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7.5–8.2 and 26–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–7.5 and 22–28 °C.
They share water: pH 7–7.5 and 22–28 °C.
They share water: pH 7–7.5 and 24–28 °C.
They share water: pH 7–7.5 and 24–28 °C.
They share water: pH 7–7.5 and 24–27 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–7.5 and 22–26 °C.
They share water: pH 7.5–8.5 and 24–28 °C.
They share water: pH 7.5–8.5 and 24–28 °C.
They share water: pH 7–7.5 and 22–26 °C.
They share water: pH 7–7.5 and 22–26 °C.
They share water: pH 7–7.5 and 22–26 °C.
They share water: pH 7–8 and 25–28 °C.
They share water: pH 7–8 and 22 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 22–24 °C.
They share water: pH 7–8 and 22–27 °C.
They share water: pH 7–7.5 and 22–28 °C.
They share water: pH 7–8 and 22–26 °C.
They share water: pH 7–8 and 22–27 °C.
They share water: pH 7–8.2 and 22–26 °C.
They share water: pH 7–8 and 25–28 °C.
They share water: pH 7–8 and 23–27 °C.
They share water: pH 7–7.5 and 23–28 °C.
They share water: pH 7–8 and 24–28 °C.
They share water: pH 7–7.5 and 22–26 °C.
They share water: pH 7–7.5 and 23–27 °C.
They share water: pH 7–8 and 22–26 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–7.5 and 22–27 °C.
They share water: pH 7–8 and 22–28 °C.
Compatible invertebrates
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–25 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8.5 and 22–28 °C.
They share water: pH 7–8.2 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–7.5 and 22–27 °C.
They share water: pH 7–7.5 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–7.5 and 23–28 °C.
They share water: pH 7–8 and 23–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8.5 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8 and 22–28 °C.
They share water: pH 7–8.5 and 22–28 °C.
Sources
- FishBaseFroese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication.
- Seriously FishSeriously Fish. Poecilia velifera. Ficha de especie; consultada 2026-10.
Water: FishBase gives pH 8, 13-19 dH and 25-28 °C; Seriously Fish, pH 7-8.5, 15-35 dGH and 22-28 °C. The wider range is used: pH 7-8.5, 13-35 dGH and 22-28 °C. Size: 15.0 cm TL in FishBase and 150 mm SL in Seriously Fish. Tank: Seriously Fish asks for a 91 × 38 cm base (104 l) and the largest possible: in a small one the male does not develop the dorsal fin well. Salinity: both sources admit fresh and brackish water, and so does the profile. Status: the IUCN lists it as Vulnerable. Name: it has no common name in real use in Spanish; the profile uses the binomial. In English it is the «giant sailfin molly». It cannot be called «molly velífera» or «molly de aleta de vela», which are the names of the Poecilia latipinna profile. The two are told apart as juveniles by counting the dorsal-fin rays: 18-19 in this one and 14 in latipinna.
Litres per fish and minimum tank height and depth: the profile's own judgement. Seriously Fish gives only the tank base and FishBase gives no tank sizes.
Lifespan: the profile's own estimate; the sources consulted do not give it.
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