molly fish

Molly Overview

Scientific Name: Poecilia sphenops
Origin: Central and South America
Adult Size: Up to 10 cm (around 4 inches)
Temperament: Peaceful and social
Difficulty Level: Beginner to intermediate
Tank Size: 75L+
Temperature: 24–28°C

Mollies are adaptable, colourful freshwater fish that are best kept in groups. They are hardy and tolerant of a range of water conditions, making them ideal for beginner and intermediate aquarists. Mollies enjoy planted tanks with open swimming areas, and their active, social behaviour makes them a lively addition to community aquariums.

Aquarium Requirements for Molly

Mollies are hardy and adaptable fish but thrive best in a stable, well-maintained aquarium.

Typical aquarium conditions include:

  • Tank Size: 75 litres or larger recommended

  • Temperature: 24–28°C

  • pH Range: Around 7.0 – 8.5

  • Filtration: Good-quality filtration with moderate flow

  • Aquarium Type: Planted or open aquascapes with plenty of swimming space

Mollies enjoy warm water and stable conditions, though they can tolerate a wider range than more sensitive species. Regular maintenance and water testing will help keep them healthy and active.

Feeding 

Mollies are omnivorous and require a varied diet to stay healthy and colourful.

Recommended foods include:

  • High-quality tropical fish flakes or pellets

  • Live or frozen foods such as brine shrimp or daphnia

  • Blanched vegetables, like zucchini or spinach

Feed 2–3 times daily in small amounts that can be consumed within a few minutes. Overfeeding can affect water quality, so moderation is important

Behaviour and Tank Mates

Mollies are peaceful, social fish that enjoy living in groups of 3–5 or more.

  • Temperament: Calm and active, often exploring all areas of the tank

  • Tank mates: Compatible with other peaceful community fish, including tetras, danios, and other livebearers

  • Avoid: Aggressive or much larger fish that may outcompete mollies for food or nip fins

Their social behaviour and colourful appearance make them a lively, engaging addition to a community aquarium.

Setting Up a Molly Aquarium

To create a comfortable home for mollies:

  • Provide a tank of 75L or larger with open swimming areas

  • Include live plants and décor to create hiding spots and territories

  • Maintain stable water quality with regular testing and partial water changes

  • Use moderate filtration to keep the water clean without producing too strong a current

  • House mollies in small groups, as they thrive in social clusters

Mollies at Smith’s Aquatics

At Smith’s Aquatics in Stockton-on-Tees, we regularly stock a selection of Molly varieties, featuring different colours and patterns.

Our team can help you with:

  • Choosing healthy fish

  • Planning a suitable aquarium setup

  • Selecting compatible tank mates

  • Advice on feeding and maintenance

If you are interested in keeping Mollies, visit our store to speak with our aquatics team and learn more about these impressive tropical fish.