Molly
Poecilia sphenops
Photo: Wikipedia / Wikimedia Commons
Needs harder, more alkaline water than the average tetra tank, and more space than the bag suggests. Short-finned mollies in 20+ gallons, not a 5.
A livebearer that actually grazes algae.
In the tank
- Picks green film off glass and décor more than guppies do.
- Still produces waste — they are not a filter.
- Water
- freshwater
- Temperament
- Peaceful
- Swims
- Midwater
- Adult size
- 4 in
- Minimum tank
- 20 gal
- Group
- Can be kept singly
- Temperature
- 72–82°F
- pH
- 7.5–8.5
- Diet
- Flakes, pellets, and algae wafers — they graze constantly.
- Beginner
- Not a first fish
How to keep them
- Hard, alkaline water. 20+ gallons for short-finned adults.
- They want some algae or veggie matter in the diet.
Tankmates
Other livebearers, hardy community fish in hard water.
Avoid
Soft acidic tetra tanks and tiny cubes.
Check tankmates · Stocking calculator
Same group
Guppy
Poecilia reticulata
Colorful livebearer. A population bomb if you mix sexes.
They pick leftover flakes and biofilm.
Endler's Livebearer
Poecilia wingei
A smaller, wilder guppy.
Grazes biofilm in planted nanos.
Platy
Xiphophorus maculatus
Sturdy livebearer for hard tap water.
Grazes a bit of algae and leftover food.
Swordtail
Xiphophorus hellerii
A bigger livebearer that uses the full water column.
Active swimmer in a 20 long.