Swamp Guppy

About

This fish is sold beside guppies, under guppy names — Maidenhead Aquatics files it as "Picta Swamp Guppy" and adds that it "may also be seen on sale as the Scarlet Livebearer" — and that is precisely how it gets killed. It is not a guppy variant. It is a hard-water, brackish-leaning estuary fish, and the soft-to-neutral community tank that a guppy shrugs off is a slow sentence for this one. The numbers are not subtle. FishBase gives "pH range: 7.5 - 8.2; dH range: 20 - 40" and 26-28 °C. Maidenhead's parameter line reads "Hard and alkaline conditions preferred. pH: 7.2-8.5, dH: up to 25 degrees. Can also be acclimatised to mildly brackish water." A dH floor of 20 is harder than most European tap water and far harder than the RO-cut, blackwater-ish tank a shop's tetra shelf points a beginner towards. Both Maidenhead and Aquadiction then say the same thing about salt in almost the same words: many collections come from brackish areas and the fish "tend to fare much better and have less health issues when maintained under slightly brackish conditions in captivity; they are also more likely to breed in such water". Wikipedia explains why from the wild side. Micropoecilia picta shares its whole range with the common guppy, but "gradually disappears from upstream freshwater sites due to competition with P. reticulata, which in turn avoids higher levels of salinity". The two species divide the estuary between them along the salt gradient — the guppy takes the fresh end, picta takes the salty end. Buy picta and put it where a guppy would be happy and you have put it on the losing side of that gradient. Given the right water it is a genuinely lovely nano livebearer. Males are about 3 cm and come in standard, red and gold wild morphs — silver to green bodies with black speckling, or a vivid red with black and yellow spots; females are larger (FishBase gives 5.0 cm TL against 3.0 cm for males), silvery, and plainer. Aquadiction is honest about the trade-off: "it is important to note their delicate nature, which renders them less suitable for novice aquarists".

Care

Hard, alkaline, warm and mature. 26-28 °C is the only temperature band any source consulted prints, so treat it as the range rather than a preference. Target pH 7.5-8.2 and at least 15 °dGH — if your tap water is soft, this is a fish you buffer for, not one you keep on RO. A quarter to a half teaspoon of marine salt per litre (SG around 1.002-1.005) is optional but is what both Maidenhead and Aquadiction say makes the difference to health and breeding. Keep six or more with at least two females per male: Maidenhead's reason is blunt — "in order to prevent any one female from becoming exhausted by the continual amorous intentions of the males". Heavily plant it with species that tolerate a little salt, keep flow gentle, and never add them to a tank that is not biologically mature. Species-only is the safest option; otherwise small, peaceful tankmates that also want hard alkaline water. No source consulted prints a minimum tank size, so this entry uses 45 litres over a 60 cm base — a step above our guppy gate, because picta is the more delicate of the two and wants the extra stability.

Diet

Small mouths, mixed diet. Good flake plus fine frozen foods — daphnia, cyclops, Artemia nauplii, mini bloodworm. It grazes some algae as well, which Maidenhead puts down to the micro-life living in it.

Telling males from females

What works for this species, most reliable first.

• The gonopodiumDefinitive · from about 4 weeks old

  Look at the anal fin, underneath and just behind the belly. In females it stays a broad triangular fan. In males it narrows into a rod and angles forward — that rod is the gonopodium, a rebuilt fin rather than an organ that appears from nowhere.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Swamp Guppy need?

A Swamp Guppy needs an aquarium of at least 45 litres (11.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Swamp Guppy need?

Swamp Guppy does best at 26–28 °C (78.8–82.4 °F), pH 7.2–8.5 and a general hardness of 15–30 °dGH.

What group size does a Swamp Guppy need?

Swamp Guppy is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Swamp Guppy suitable for beginners?

Swamp Guppy is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.

Sources

• FishBase — Poecilia picta (Swamp guppies)
• Maidenhead Aquatics — Picta Swamp Guppy (Micropoecilia picta)
• Wikipedia — Poecilia picta (swamp guppy)
• Aquadiction — Picta Swamp Guppy (Micropoecilia picta)