Many mollies reach 3 to 4 inches or more; sailfin types need even more swimming room.

Compact livebearer, often around 2 inches or a bit more; easier to keep a small group in a modest tank.

Several years with good water; chronic issues appear if salinity or hardness needs are ignored.

Typically 2 to 4 years in home aquaria with stable water and controlled breeding load on females.

Active fish that benefits from a longer tank and some open swimming lanes as it grows.

Moderately active; appreciates plants and a bit of current but does not need as much length as large mollies.

Higher bioload as size increases; watch algae and waste. Some keepers add aquarium salt or marine mix carefully.

Standard freshwater maintenance; frequent small water changes help because fry can appear often.

Recognizes feeding; no meaningful training. Behavior is social within the group.

Same limited interaction; enrichment is tank layout and compatible tankmates.

Hardy personality for viewing; teach kids about livebearer breeding so tanks do not overcrowd.

Colorful and peaceful for families; discuss separating sexes or providing fry plans before surprise babies.

Fin fungus, parasites, and shimmying can reflect chemistry mismatch; research your strain's preferred conditions.

Generally robust in stable freshwater; still watch for ich after purchase stress and avoid overcrowding.

Affordable fish; larger tank and possible salt-related supplies can raise setup cost.

Very budget-friendly per fish; main costs are tank, filter, and managing a growing population.