Gill's Molly

Poecilia gillii

Gill's Molly (Poecilia gillii) — Easy care, Semi-aggressive, under Livebearer & Killifish. Minimum tank in the app: 26 US gal min; aim for 72–86°F and pH 6.8–8.2. Gill's Molly is an engaging choice for aquarists who appreciate active, sociable fish that thrive in groups.

Gill's Molly (Poecilia gillii) in a planted freshwater aquarium
Care levelEasy
TemperamentSemi-aggressive
Min tank size26 US gal min
pH range6.8–8.2
Temperature72–86°F
Max size3.9 in (10.0 cm)
Captive lifespan2–4 years
SchoolingYes · 6+ recommended

Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.

Natural distribution

Americas / Africa (varies)

  • Africa
  • South America
  • Central America & Mexico

Regional colours match the stocking calculator’s origin map.

Gill's Molly Tank Setup

Create a spacious tank with plenty of mid-level swimming room and strategically placed plants or decorations to provide cover without obstructing swimming paths. A gentle flow suits their natural habitat, while a darker substrate can enhance their colouration. Ensure lighting is moderate to mimic their native environments.

What Do Gill's Mollys Eat?

These omnivores exhibit varied feeding speeds, with some individuals competing for food. To promote health and colour vibrancy, offer a balanced diet, including high-quality flakes, pellets, and occasional live or frozen foods.

Gill's Molly Tank Mates

Gill's Molly pairs well with similarly sized, peaceful species that occupy different zones, such as small tetras or rasboras. Larger, aggressive fish can pose a threat, especially in confined spaces. When kept with their own kind, maintain groups of at least six to prevent bullying; however, be cautious of overstocking to manage bioload.

Are Gill's Mollys Good for Beginners?

In App-aquatic we file this under easy care. That still means a cycled tank, realistic stocking, and parameters that do not swing every weekend. Aquarists often underestimate the importance of group size, leading to territorial disputes and stress. neglecting water quality parameters, particularly pH and temperature, can result in health issues.

Building a community? Run the full list through the stocking calculator before you add anything else.

Log tests and reminders in App-aquatic—free, same data you see here.