Liberty Molly (Poecilia salvatoris)

Recognise the Liberty Molly

The Liberty Molly is Poecilia salvatoris, a freshwater member of the family Poeciliidae. FishBase places the species in El Salvador and describes it as tropical and benthopelagic. Those details identify the wild fish; aquarium decisions still need to be based on stable water, suitable group space and the needs of every animal sharing the tank.

A Wikipedia summary of the Liberty Molly identifies it as one of the short-fin mollies in the Poecilia sphenops complex. It was often treated as synonymous with P. sphenops, but its recognised species name is Poecilia salvatoris.

Who it suits

This molly suits a keeper prepared to maintain a mature biological filter, test the water every week and keep a companion group rather than a lone fish. Guppies and mollies are generally described as undemanding aquarium inhabitants, but that does not remove the need for zero ammonia, zero nitrite and controlled nitrate.

Its peaceful molly-group temperament makes it a candidate for a carefully planned community, provided the other fish suit the same temperature, pH and hardness. Compatibility depends on the whole aquarium rather than a fixed list of names. If you are comparing related forms before deciding, browse the molly fish collection and compare their stated adult-space and water requirements.

Understand the fish supplied

One purchase supplies one animal. The dispatch grade for this offer is 3–6 cm; that measurement describes the fish sent rather than its final adult size. Plan the aquarium around the group and its longer-term space requirements.

Sex is guaranteed only when the selected option explicitly states male or female. This Liberty Molly listing has no sex-guaranteed option.

Read the gallery correctly

The pictured fish shows the metallic silver-gold appearance, dark-edged scales and spotted translucent fins visible in the gallery scene. The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal.

Do not use the gallery to decide the sex, age or exact appearance of the fish supplied. Plan the social group without assuming that a particular photograph corresponds to the animal sent.

Separate dispatch size from aquarium planning

A fish within the 3–6 cm dispatch grade still needs an aquarium selected for a molly group rather than a container chosen around its arrival measurement. Allow swimming room, shelter and sufficient filtered volume for the complete stocking plan. If other fish will share the aquarium, include their eventual space and waste load before adding the Liberty Molly.

Plan around the core care numbers

OATA’s guppy and molly guidance gives 20–28°C, pH 7.0–8.0, general hardness of 8–18°dH and carbonate hardness of 5–15°dKH for the group; these are broad aquarium values rather than a species-specific optimum. It also recommends at least 45 litres for a small group of the smaller forms and suggests keeping at least three for companionship.

Allow for the molly growth reference

OATA notes that mollies stay below 10 cm, while sailfin mollies can reach approximately 15 cm. The Liberty Molly is identified as a short-fin molly, so the below-10 cm molly figure is the relevant group planning reference rather than the sailfin figure. Treat it as a space-planning guide, not as a guaranteed final measurement for an individual fish.

The 45-litre recommendation applies to a small group of smaller guppies or mollies. Increase the volume when the aquarium contains more groups or additional community fish. A larger volume also makes temperature and water quality more stable, but it still requires filtration, testing and maintenance.

Hold water inside the working range

Keep the aquarium between 20 and 28°C, with pH from 7.0 to 8.0, general hardness from 8 to 18°dH and carbonate hardness from 5 to 15°dKH. Choose a steady point within those ranges that also suits every other fish in the aquarium. Stability matters more than moving repeatedly between the lower and upper limits.

Test the values that affect daily welfare

Measure the aquarium rather than judging water by appearance. Our water chemistry guide explains what the main readings mean, while the water matcher lets you compare measured values with the working ranges above.

Respond to an unsafe reading in the right order

1. Pause further stocking. Additional fish and food increase the waste that the biological filter must process.
2. Check the filter. Confirm that it is running and not blocked.
3. Carry out the scheduled partial water change. Treat replacement tap water with conditioner before it enters the aquarium.
4. Retest. Ammonia and nitrite must return to zero before the aquarium receives more livestock.

Do not use a higher pH, greater hardness or warmer temperature as a substitute for clean water. The chemistry range and the nitrogen-cycle readings are separate decisions, and both must be suitable at the same time.

Build biological filtration before stocking

A working filter is essential. The RSPCA’s aquarium welfare guidance explains that fish release toxic ammonia, which a biological filter processes first into nitrite and then into the safer nitrate. Beneficial bacteria perform that conversion, so the filter must be established and maintained rather than treated as a simple device for clearing visible debris.

Prepare the aquarium before the fish arrives

Use a well-matured setup with suitable temperature and water chemistry. Test for zero ammonia and zero nitrite before adding fish. If this is your first setup, follow our first tropical aquarium guide while preparing and maturing the filter.

Add livestock slowly. Every additional fish and every increase in feeding adds waste, while the beneficial bacterial population needs time to adjust. Stocking too quickly can cause new tank syndrome, in which the filter bacteria cannot process the rising ammonia and nitrite.

Use a simple readiness check

• Filter: running continuously, established and free of blockages.
• Temperature: stable within 20–28°C.
• Water chemistry: pH 7.0–8.0, general hardness 8–18°dH and carbonate hardness 5–15°dKH.
• Nitrogen readings: zero ammonia and zero nitrite.
• Space: at least 45 litres for a small molly group, with more volume for additional stocking.
• Cover: substrate plus live plants, artificial plants or suitable ornaments that provide shelter.

A larger aquarium can provide more stable environmental conditions, but volume alone does not mature a filter. Confirm readiness with test results and build the population gradually.

Give the group space and cover

Start with an aquarium of at least 45 litres for a small group of the smaller molly forms. Increase that volume when adding more fish or combining several groups. Space planning must cover the complete community, not only the 3–6 cm dispatch measurement of the first Liberty Molly.

Divide the aquarium into useful areas

• Swimming room: leave enough unobstructed water for the group to move without crowding.
• Shelter: use live plants where practical, or provide artificial plants and suitable ornaments when live plants are not used.
• Substrate: aquarium gravel or sand gives the setup a suitable base.
• Service access: keep the filter and substrate reachable for weekly checks and waste removal.

The purpose of cover is to give fish places to shelter and to break up an otherwise open aquarium. It does not compensate for insufficient volume or unsuitable tank mates. Likewise, open swimming room does not replace the need for planted or decorated refuge.

Scale the aquarium when the plan changes

A 45-litre aquarium is the starting recommendation for a small group, not a universal allowance for every combination of fish. Recalculate the plan before adding another social group, more mollies or any community companions. More fish mean more feeding and waste, so the filter’s capacity and the weekly maintenance burden increase alongside the stocking level.

Use the below-10 cm figure for non-sailfin mollies as a group planning reference when judging swimming room. Do not size the aquarium around the smallest fish on arrival. The goal is to avoid a later move caused by treating dispatch size as final size.

Work through a stocking change before acting

For example, a 45-litre aquarium planned for the initial small molly group should not automatically receive a second group simply because open water remains visible. First total the intended animals, check the space needs of every group and consider how the added daily food will affect waste production. Confirm that shelter remains usable without removing too much swimming room, and make sure the filter can stay accessible for weekly maintenance.

If the plan changes from a molly-only group to a mixed community, reassess the aquarium before buying the companions. Keep the 45-litre figure attached to the small molly group rather than treating it as a complete community allowance. Choose more volume when the combined plan needs it, then establish and test the filter before the extra livestock arrives.

Feed once with an algae-rich staple

Feed once a day, offering only what the fish consume within a few minutes. Use a good-quality flake or granule with a high algae content as the staple food. This follows the omnivorous feeding pattern used for guppies and mollies while keeping the routine simple enough to measure.

Add variety in small portions

Small live or frozen foods such as daphnia, small bloodworm or tubifex can supplement the staple. These additions provide variety, but they do not replace the algae-rich flake or granule as the routine aquarium food.

Use the aquarium to judge the portion

Watch the feeding rather than adding an unmeasured amount and leaving the tank. If food remains after a few minutes, reduce the next portion. Uneaten food breaks down and releases waste, which can raise the burden on the biological filter and damage water quality.

When several fish share the aquarium, observe whether every animal reaches the food. A reduced appetite or loss of interest in feeding can be an early health warning, particularly when it occurs alongside changed swimming, breathing, colour or hiding. Check the water readings before changing the diet, because ammonia or nitrite can affect the whole group.

Do not add extra meals simply because the fish finish quickly. The stated routine is once daily within a few minutes; portion control protects water quality and gives you a consistent baseline for noticing a genuine change in appetite.

Set a repeatable first-week baseline

During the first week, feed at the same daily point when practical and watch the complete few-minute feeding period. Note whether the portion disappears cleanly, whether food reaches each fish and whether any pieces remain on the substrate. Reduce the next portion when food remains; do not compensate with a second meal later that day.

Compare appetite with swimming, breathing and hiding rather than interpreting feeding in isolation. If several fish lose interest together, test ammonia and nitrite and check the filter before offering a different food. Once the portion is consistently consumed without leftovers, keep that amount as the routine baseline and use the listed live or frozen foods only as small supplements.

Complete the weekly maintenance cycle

Change 25% of the aquarium water at least once every week. Use a siphon to remove solid waste from the gravel where needed, and treat all replacement tap water with conditioner before adding it. Conditioner is required to remove harmful chlorine or chloramine.

Combine the jobs into one routine

1. Test first. Measure ammonia, nitrite and the other water values so you know the aquarium’s condition before maintenance.
2. Remove 25%. Siphon out water and accessible solid waste without stripping the aquarium down.
3. Retain some removed water. Use it if the filter media needs a light rinse.
4. Condition replacement water. Treat tap water before it enters the aquarium.
5. Refill and recheck equipment. Confirm that the filter is running and free of blockages.

Protect the filter bacteria

Never rinse filter media under the tap. Chlorine or chloramine may kill part of the beneficial bacterial population established in the media. Rinse it lightly in water removed during the partial change, and clean it only when necessary rather than trying to make biological media look unused.

The weekly water test and water change serve different purposes. Testing reveals whether ammonia or nitrite is present and tracks nitrate; the partial change removes dissolved waste and refreshes the aquarium. Completing one does not replace the other.

Use results to control stocking

If ammonia or nitrite appears, do not add more fish. Check the filter, review whether feeding has increased and continue testing after corrective maintenance. Nitrate should remain no more than 20 mg per litre above the normal tap-water level. Compare aquarium and tap-water results rather than relying on an isolated nitrate number.

A stable weekly record makes changes easier to recognise. Use the same tests and routine intervals so a rising reading reflects a real change in stocking, feeding or filtration rather than inconsistent monitoring.

Acclimatise before release

Arrange for someone to receive the parcel because live fish must not be left unattended. Before opening the bag, check that the prepared aquarium is within 20–28°C and that ammonia and nitrite are zero.

Follow the arrival sequence

1. Start filming before the sealed parcel is opened. Keep filming continuously as the parcel is opened and show the fish still inside the sealed bag.
2. Float the bag for 20–30 minutes. Keep the bag closed throughout this period.
3. Release the fish without pouring bag water into the aquarium. Keep transport water separate from the prepared setup.

The store’s delivery and Live Arrival Guarantee policy carries the current receiving instructions and claim requirements. Read it before the delivery date so someone can be present and the required arrival checks can be completed in the stated order.

OATA advises watching swimming, breathing, colour, condition and interest in food over the following days. Compare what you see with the fish’s usual behaviour and test the aquarium if anything changes.

Prepare the destination, not just the temperature

Floating the bag does not correct an immature aquarium, unsuitable pH or measurable ammonia and nitrite. Complete the filter maturation, group-space planning and water testing before dispatch. The fish should move into a stable, filtered setup rather than an aquarium still being adjusted.

Do not add several further fish immediately after arrival. Increase stocking slowly so the biological filter has time to adapt to the added waste and feeding. Continue the normal once-daily feeding limit and weekly testing rather than increasing food to encourage a newly introduced fish.

Use clear arrival checkpoints

• Before receipt: confirm the filter is running, the temperature is within 20–28°C and both ammonia and nitrite read zero.
• At receipt: begin filming with the parcel still sealed and continue as it is opened until the fish is shown inside the sealed bag.
• During floating: keep the bag closed for the full 20–30 minutes and prepare to keep its water out of the aquarium.
• At release: transfer the fish without pouring transport water into the tank.
• Over the following days: continue the normal feeding and testing routine so any change can be compared with a consistent baseline.

If swimming or breathing changes, test the shared environment first and confirm that the filter remains operational. Avoid responding to a newly introduced fish by adding extra food or more livestock. Stable care makes it easier to distinguish a brief settling response from a change that needs further action.

Act on changes early

Learn the group’s usual appearance and behaviour so a change is noticeable. Healthy fish should have clear, bright eyes, intact scales and undamaged fins, without ulcerations or bumps. Observation works best alongside regular water testing rather than as a replacement for it.

Use each warning sign as an action prompt

Check the shared environment first

When several fish change at once, test ammonia, nitrite, nitrate, temperature and pH promptly and confirm that the filter is operating. Water problems can affect the whole aquarium, so correcting the environment takes priority over guessing at a disease from one visible sign.

If a health change persists, test the water and contact us for further guidance. Record the readings and the changes in swimming, breathing, appearance and feeding so the next decision is based on concrete observations. Do not begin a treatment routine from appearance alone.

Screen every tank mate before mixing fish

Mollies are generally peaceful and compatible with many other fish, but no named species is an automatic match. Judge each proposed companion against the aquarium’s temperature, pH, hardness, adult-space requirement, social needs and behaviour.

Apply the screening sequence

1. Compare temperature. The companion’s normal aquarium range must overlap 20–28°C.
2. Compare pH. It must share a workable point within pH 7.0–8.0.
3. Compare hardness. It must suit general hardness of 8–18°dH and carbonate hardness of 5–15°dKH.
4. Recalculate space. Keep the Liberty Molly group allowance and add the needs of the proposed companion rather than trying to fit every fish into the original 45 litres.
5. Check social pressure. Watch for increased aggression, hiding, feeding changes, damaged fins or altered swimming after introduction.

Use a shared working point

A temperature appearing in both species’ outer ranges is only the first test. The pH and hardness must also overlap, and the chosen values must be maintainable in your tap water and aquarium. A peaceful label cannot solve conflicting water requirements.

Allow cover as well as swimming room. Plants or suitable ornaments provide shelter, while open space reduces crowding. These features support a compatible plan but cannot turn insufficient volume into a suitable community.

Reject a proposed combination when the fish require conflicting water or when the complete group plan exceeds the aquarium’s capacity. When the ranges overlap, introduce livestock gradually and observe the actual interactions. Contact us for a stocking and compatibility assessment if you want the full community checked before ordering.

Manage the social group without overcrowding

Plan at least three guppies or mollies because the group guidance says they require companionship. One purchase supplies one Liberty Molly, so the number ordered and the fish already present must together meet the intended social plan.

Account for sex without assuming it

Where males and females are known, the suggested ratio is two females to each male to reduce stress on females and other inhabitants. Apply that ratio only when the sexes are known; do not infer sex from dispatch size, colour or the representative gallery.

Guppies and mollies are livebearers and give birth to live young. A mixed-sex plan can therefore increase the number of fish, so leave enough filtered space and avoid treating the starting headcount as permanent. Include that possible population increase when calculating space and filtration.

Add the group in controlled stages

Confirm zero ammonia and zero nitrite before increasing the population. Add fish slowly because beneficial filter bacteria need to increase as stocking and feeding rise. Test after each stocking change and postpone the next addition if either toxic reading appears.

Watch the established group after every introduction. More aggression, hiding, altered swimming or reduced feeding signals that the social or environmental plan needs attention, even when the water values still test within range.

Answer the key Liberty Molly questions

What is Poecilia salvatoris?

It is a short-fin molly species from El Salvador in the family Poeciliidae.

How many Liberty Mollies does one purchase supply?

One purchase supplies one animal. Plan the final group separately.

What dispatch size should I expect for a Liberty Molly?

The dispatch grade is 3–6 cm. This is the size sent, not an adult-size promise, so allow for growth when planning space.

What aquarium does a Liberty Molly need?

OATA’s molly-group guidance recommends a mature, filtered aquarium of at least 45 litres for a small group, with substrate and plant or ornament cover; increase the volume as stocking grows.

Should Poecilia salvatoris be kept alone?

OATA’s molly-group guidance suggests keeping at least three because these fish require companionship. Add fish gradually so the biological filter can adjust.

What water range suits the Liberty Molly?

OATA’s molly-group guidance gives 20–28°C, pH 7.0–8.0, general hardness of 8–18°dH and carbonate hardness of 5–15°dKH; keep ammonia and nitrite at zero.

What should this fish eat?

Feed an algae-rich quality flake or granule once daily, limited to what is eaten within a few minutes, with small live or frozen daphnia, bloodworm or tubifex for variety.

How should I acclimatise it?

Start filming before opening the sealed parcel and continue without a break as it is opened, showing the fish still inside the sealed bag. Then float the bag for 20–30 minutes before release, keep bag water out of the aquarium and ensure someone receives the parcel.

Which tank mates suit it?

Choose peaceful fish whose temperature, pH and hardness needs overlap, then assess adult space, social requirements and observed behaviour after introduction.

Check the reference scope

• FishBase: scientific identity, family, freshwater environment and El Salvador distribution.
• Wikipedia: Liberty Molly natural history and short-fin molly classification.
• OATA: guppy and molly aquarium guidance for water, group planning, feeding, maintenance and observation.
• RSPCA: general aquarium filtration and biological waste-processing welfare.
• Tropical Fish Co delivery policy: receiving, acclimatisation and Live Arrival Guarantee terms.