🏠The Molly tank: 100 L, hardware and start-up
Molly : A tank of at least 100 L, fairly tall and long, for a group with a majority of females. A prolific species: plan ahead for the many fry.
In short: 6 to 10 cm as an adult, 100 L minimum for a group, hard water between 24 and 28 °C. Active, sociable and a keen grazer, it enlivens the surface and decor all day in a female-dominant group. It needs warm, hard, alkaline water: in soft acidic water it quickly develops the shimmying disease.
100 litres minimum: why that number
For a group of 5+ Molly reaching 10 cm as an adult, plan 100 real litres — and remember a big tank is more STABLE, hence easier, than a small one: parameters drift slowly, leaving time to correct. This volume suits a sturdy standard cabinet — just verify perfect levelness.
Hardware: filter, heater, lighting
The Molly tank’s technical trio starts with filtration — three to five volume turnovers per hour, a heater around 1 W per litre set to 24 to 28°C, backed by an independent thermometer — built-in thermostats sometimes lie, and lighting on a timer at 8 to 10 hours a day: any longer and the algae win.
Substrate, plants and start-up
Nutrient substrate under fine sand or quartz, robust plants (anubias, vallisneria, Java moss) and wood to structure the territory. Then patience: a complete nitrogen cycle (3 to 4 weeks, nitrites back to zero) before the first Molly — the step every hurried beginner pays for dearly.
Frequently asked questions
What tank size for Mollys?
A real 100 litres minimum for a group of 5+ — below that, parameters drift too fast to catch.
Does a Molly need a heater?
Yes, about 1 W per litre set to 24 to 28°C, with an independent thermometer double-checking the thermostat.
The guides that apply to you
- Setting up a 60-litre freshwater aquarium: the key steps
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- Lake Malawi African Cichlid Aquarium: Hard Water and Décor
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- How many fish in a 60-litre aquarium? The realistic calculation
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