Platies Optimal Platy Water Parameters: Temperature, pH, GH, more

Optimal Platy Water Parameters: Temperature, pH, GH, more

Platy fish are a fun and colorful fish that are becoming increasingly popular in the fishkeeping hobby. Although these livebearers can be a great addition to most community tanks, many people experience issues when their water parameters are not on point.

This article explains the optimal water parameters to maximize the quality of life for your platy fish.

Ideal water parameters for platies

Fish speciesPlaty fish
Temperature range75-80°F (24-27°C)
pH range7.5-8.5 pH
General hardness (GH range)10-20 dGH (178-356ppm)

75-80°F (24-27°C) is the best temperature for platy fish

Platy fish are tropical freshwater fish that require a tank temperature between 75-80°F (24-27°C). They are native to Mexico, Guatemala and Honduras, where the average annual temperature is between 73-80°F (23-27°C) in the coastal lowlands.

100-watt heater for our 20-gallon tank

Platies will tolerate temperatures outside of this range as well. This most important thing is maintaining a constant temperature to reduce stress.

Platy fish do best in 7.5-8.5 pH

Platy fish tend to do best in a pH range between 7.5-8.5 because alkaline water contains more dissolved minerals, such as calcium and magnesium. Most experts agree that maintaining a stable pH is more important to platy health than achieving a specific pH value.

Our tap water is about 8.0-8.2 pH

Studies confirm that water on each extreme of the pH scale (4.0-6.5 pH and 9.0-11.0 pH) are dangerous and will stunt growth, prevent reproduction and cause death in fry. Other sources suggest that pH is less important as long as it falls within a fairly neutral range of 6.5-8.5 pH.

10-20 dGH (178-356ppm) is the best general hardness for platy fish

Platy fish prefer slightly alkaline and moderately hard water. Calcium ions present in hard water helps with bone and tissue development. It is also believed that hard water plays a role in livebearer immunity.

Our GH ranges between 15-19 dGH depending on the time of year

How to test your water parameters

Tap water sourced from rivers tends to have higher pH and hardness levels. Most cities publish reports online from their water treatment plants, which can be used as an estimate.

A more accurate water testing method is using a liquid API Freshwater Master Test Kit to test your tap water’s water parameters. Water parameters in your aquarium may differ from your water treatment plant due to many factors, including plants and livestock.

API Liquid Master Test Kit

Can platies live in cold water?

Platies are happiest, most active and will be more likely to spawn in water between 73-80°F (23-27°C). It’s not recommended to keep platies in cold or room temperature water.

Do platy fish need salt?

Platy fish do not require salt but are known to benefit from living in low concentrations of saline water. In fact, many platies are bred abroad in brackish water, which has a much higher salt concentration than what typical freshwater aquariums contain.

Platies can certainly tolerate salt. Aquarium salt is often used to treat bacterial infections and some parasites. This treatment is applied either directly to a display tank or in shorter durations via a salt bath or salt dip.

Do platies need a heater?

Platies do not require an internal aquarium heater if the room has a temperature between 75-80°F (24-27°C). Some fishkeepers with many tanks choose to heat their entire fish room instead of purchasing internal heaters for each tank.

How fast can I raise the temperature in a platy tank?

It’s safe to raise an aquarium’s temperature by 2 degree Fahrenheit per day, or 1 degree every twelve hours. Rapid temperature change may cause stress among your fish, which lowers their immunity and makes them more susceptible to illness. A more rapid temperature is unlikely to have detrimental effects but is not recommended if you have the choice.

Ryan Ferguson

Founder, Rooted Tank

Ryan Ferguson, the founder of Rooted Tank, started fishkeeping in 2019. He has continued to level-up his planted aquarium skills and wanted to share his journey and knowledge with other aquarists.


227, 25 Auburn Meadows Avenue SE, Calgary, Alberta, Canada, T3M 2L3