Amazon molly
Poecilia formosa
Also known as Mollienesia formosa, Limia formosa
FreshwaterFish
Care at a glance
- Temperature
- 68–82°F
- 20–28°C
- pH
- 7.0–8.2
- Adult size
- 3.5 in
- 9 cm
- Minimum tank
- 20 gal
- 75 L
- Temperament
- Peaceful
- Social behavior
- Social
- Swim level
- Middle
- Difficulty
- Easy
- Breeding
- Medium
- Rarity
- Rare
- Family
- Poeciliidae
- Origin
- Native to the lower Rio Grande and Rio Panuco drainages of southern Texas and northeastern Mexico, in warm, often hard coastal waters.
Overview
Keep in 75 liters or larger at 20 to 28 C, pH 7.0 to 8.2, in hard water, ideally with a few sailfin, shortfin, or Atlantic mollies present so the Amazon mollies keep breeding. Feed a vegetable rich diet of spirulina flake and blanched greens plus some frozen foods. Peaceful and easy, though like all mollies it wants warmth, hard water, and clean conditions. It tolerates slightly brackish water. Females reach about 9 cm.
In the wild
A plain silvery to olive molly that is famous less for its looks than for how it breeds. Keep a group in a hard, alkaline tank with warm, stable water and open swimming space among plants. It grazes algae and takes most prepared foods readily. Because it is all female, you need a related molly to keep it reproducing.
Good to know
Poecilia formosa is a naturally occurring all female species that arose from an ancient cross between the Atlantic molly and the sailfin molly. It reproduces by gynogenesis, meaning females must mate with a male of a related molly to trigger development, but the male's genes are not passed on and the fry are clones of the mother. It was the first unisexual vertebrate ever described.
Did you know
Every Amazon molly is female, and a wild population persists only by borrowing sperm from males of other molly species that it then discards genetically.
Weekly picks
Tank mates
Amazon molly is a peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.
Marble wood shrimp
Atya scabra
Freshwater3.9 in (10 cm) · 20 gal (75 L)73–82°F (23–28°C)
Bronze cory
Osteogaster aenea
Freshwater3 in (7.5 cm) · 20 gal (75 L)70–81°F (21–27°C)
Rex halfbeak
Nomorhamphus rex
Freshwater2.2 in (5.5 cm) · 20 gal (75 L)72–79°F (22–26°C)
Brilliant rasbora
Rasbora einthovenii
Freshwater3.5 in (9 cm) · 20 gal (75 L)72–82°F (22–28°C)
Aizawl loach
Schistura aizawlensis
Freshwater2.4 in (6 cm) · 20 gal (75 L)68–79°F (20–26°C)
Blue panchax
Aplocheilus panchax
Freshwater3.5 in (9 cm) · 20 gal (75 L)72–82°F (22–28°C)
Common questions
What size tank does an Amazon molly need?
An Amazon molly needs at least 20 gal (75 L). It spends most of its time in the middle.
What temperature and pH does an Amazon molly need?
An Amazon molly is comfortable at 68–82°F (20–28°C) with a pH of 7.0–8.2.
How big does an Amazon molly get?
An adult Amazon molly reaches about 3.5 in (9 cm).
Related species
3.9 in (10 cm)26 gal (100 L)72–86°F (22–30°C)Gill's molly
Poecilia gillii
3.9 in (10 cm) · 26 gal (100 L)
3.1 in (8 cm)20 gal (75 L)72–81°F (22–27°C)Southern molly
Poecilia vivipara
3.1 in (8 cm) · 20 gal (75 L)
4.3 in (11 cm)32 gal (120 L)72–82°F (22–28°C)Shortfin molly
Poecilia mexicana
4.3 in (11 cm) · 32 gal (120 L)
2.8 in (7 cm)29 gal (110 L)72–81°F (22–27°C)Pacific molly
Poecilia butleri
2.8 in (7 cm) · 29 gal (110 L)
2.4 in (6 cm)16 gal (60 L)77–86°F (25–30°C)Cauca molly
Poecilia caucana
2.4 in (6 cm) · 16 gal (60 L)
2.4 in (6 cm)13 gal (50 L)64–82°F (18–28°C)Guppy
Poecilia reticulata
2.4 in (6 cm) · 13 gal (50 L)