This guide covers Poecilia reticulata, a livebearing guppy with many aquarium color forms. Color names do not make those forms separate species.
OATA distinguishes the Endler guppy, Poecilia wingei, from Poecilia reticulata. Check which fish the seller means.
Poecilia reticulata summary page · How to look after guppies and mollies
What a color name tells you
Color names such as blue describe an aquarium form. They do not replace a species identification or a plan for the actual group. Record the scientific name alongside the trade name when comparing fish.
Poecilia reticulata summary page
Plan the aquarium before buying
Ask the seller for the scientific name, the fish’s expected adult size, and the size and composition of the group you intend to keep. Then check that the mature aquarium provides swimming room, cover, suitable water conditions and a gentle flow for long-finned fish. OATA recommends a filter, water test kits and advice on an appropriate aquarium for the planned number of fish. A single volume rule cannot answer all of those questions.
How to look after guppies and mollies
Make the upkeep visible
Prepare the aquarium before adding fish. A cycled aquarium has an established biological filter whose bacteria process fish waste. Clear-looking water alone does not establish that the system is ready or that its water is suitable; testing provides information you cannot get by looking.
Keep a dated record of water tests, equipment checks and maintenance. When a caregiver takes over, show them where the test kit is kept and where results are recorded.
RSPCA: creating a good home for fish
Account for live young
Guppies are livebearers. Females can retain sperm, so a female-only purchase does not by itself rule out later young. Ask about previous housing as well as the fish currently in the group, and plan where any young could be housed before stocking.
Poecilia reticulata summary page
Your next decision
Write down the exact species, adult-size expectation, intended group, available swimming space, filter, test kit and maintenance plan. Review those details with an experienced aquatic retailer before purchase.
Plan your next step
Browse fish guides · Organize pet routines · Use the free Pet Life Checklist · Molly overview · Goldfish overview
Sources and further reading
- Poecilia reticulata summary page (checked 13 October 2026)
- How to look after guppies and mollies (checked 13 October 2026)
- RSPCA: creating a good home for fish (checked 13 October 2026)
The cover shows blue guppies, one aquarium color form.