Variety of Black molly
Balloon molly
Poecilia sphenops
One of 4 varieties of Poecilia sphenops · See all varieties →
Also known as Black Balloon Molly
FreshwaterBrackishFish
Varieties · Poecilia sphenops
See all 4 →
Care at a glance
- Temperature
- 70–82°F
- 21–28°C
- pH
- 7.0–8.0
- Adult size
- 4.7 in
- 12 cm
- Minimum tank
- 24 gal
- 90 L
- Temperament
- Mostly peaceful
- Social behavior
- Social
- Swim level
- Middle
- Diet
- Omnivore
- Difficulty
- Easy
- Breeding
- Livebearer · Easy
- Rarity
- Very common
- Family
- Poeciliidae
Overview
The balloon molly is a short-bodied form of molly, and the shape is the whole point of the line. It is easy to keep in a peaceful community tank.
Did you know
Unlike most livebearer color forms, the balloon shape is contested rather than merely decorative. One hobby reference calls the abdominal cavity extremely deformed and notes the fish have been cited as an example of cruelty to animals. The references do not agree, so keeping balloon mollies is a judgment call rather than a care question.
Caring for the balloon molly
Keep balloon mollies in a small group in a tank of at least 24 gal (90 L). A planted tank with open swimming space and steady warmth suits them. Give them hard, alkaline water at 70 to 82°F (21 to 28°C) and a pH of 7.0 to 8.0. They tolerate, and often appreciate, a little salt in the water.
Balloon mollies graze algae and need real plant matter in their diet. Feed a vegetable-based flake or pellet with some protein mixed in. They swim less efficiently than a standard molly, and one hobby reference calls them poor swimmers outright. A second reference finds them lively enough, but still advises watching them at feeding time against faster tank mates.
They are mostly peaceful and safe with other community fish. Keep more females than males to spread out the males' constant chasing. Females grow larger and rounder than males, and males carry a gonopodium, a modified anal fin used to fertilize females.
Balloon mollies are livebearers and give birth to free-swimming young instead of laying eggs. They breed easily, so expect fry.
Good to know
Balloon mollies are sold in black, silver and dalmatian under the same shape label. A genome-wide association study looked at a dwarf line of sailfin molly that its authors call the balloon belly molly. It described that short form as having a short and dysplastic spine, and mapped it to two genomic regions. Hobbyists usually blame the reported problems on packing a full-length gut, swim bladder and, in females, developing fry into half the body length.
In the wild
The balloon molly is a bred deformity, not a wild form. Its rounded outline traces to a shortened, curved spine that breeders selected and then fixed. It sits on the same mixed molly stock as the other trade forms, blending the short-finned and sailfin species. The originating farm and date are not documented.
Weekly picks
Tank mates
The balloon molly is a mostly 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.
Neocaridina shrimp
Neocaridina davidi
Freshwater1.6 in (4 cm) · 5 gal (19 L)59–84°F (15–29°C)
Neon tetra
Paracheirodon innesi
Freshwater1.5 in (3.8 cm) · 11 gal (40 L)70–77°F (21–25°C)
Congo tetra
Phenacogrammus interruptus
Freshwater3.1 in (8 cm) · 24 gal (90 L)73–82°F (23–28°C)
Guntea loach
Lepidocephalichthys guntea
Freshwater4.7 in (12 cm) · 24 gal (90 L)64–82°F (18–28°C)Siamese flying barb
Laubuka siamensis
Freshwater2.6 in (6.5 cm) · 24 gal (90 L)72–81°F (22–27°C)
Peppered cory
Hoplisoma paleatum
Freshwater2.8 in (7 cm) · 21 gal (80 L)72–79°F (22–26°C)
Common questions
Is a balloon molly a different species from the black molly?
No. A balloon molly is a variety of the black molly, Poecilia sphenops, and it wants the same tank, water and food as the species.
What size tank does a balloon molly need?
A balloon molly needs at least 24 gal (90 L). It spends most of its time in the middle.
What does a balloon molly eat?
A balloon molly grazes algae and needs real plant matter in its diet. Feed it a vegetable-based flake or pellet with some protein mixed in. Watch it at feeding time against faster tank mates.
How big does a balloon molly get?
An adult balloon molly reaches about 4.7 in (12 cm).
How can you tell a male balloon molly from a female?
Males carry a gonopodium, a modified anal fin they use to fertilize females. Females grow larger and rounder than males.
How does a balloon molly breed?
A balloon molly is a livebearer and gives birth to free-swimming young instead of laying eggs. It breeds easily, so expect fry.
Related species
4.7 in (12 cm)24 gal (90 L)70–79°F (21–26°C)Sailfin molly
Poecilia latipinna
4.7 in (12 cm) · 24 gal (90 L)
3.9 in (10 cm)24 gal (90 L)72–82°F (22–28°C)Liberty molly
Poecilia salvatoris
3.9 in (10 cm) · 24 gal (90 L)
5.9 in (15 cm)30 gal (113 L)75–82°F (24–28°C)Giant sailfin molly
Poecilia velifera
5.9 in (15 cm) · 30 gal (113 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)
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)
3.5 in (9 cm)20 gal (75 L)68–82°F (20–28°C)Amazon molly
Poecilia formosa
3.5 in (9 cm) · 20 gal (75 L)