Guppy Tank Conditions: The Ideal Water Parameters for Your Guppies

This is a guest post by Peter Hartono, the founder and CEO of Just Aquatic.

Do guppies need a filter?

Don’t keep your guppy in poor quality water!

Guppies (Poecilia libestes reticulata) are one of the most popular fish species for beginners. They are quite hardy and can easily adjust to fluctuations in water conditions than most species of fish.

Guppies are endemic to the fresh and brackish waters of the Amazon River and on several islands in the Caribbean. It is one of the smallest live-bearing fish species, with females reaching only 2.5 inches and males slightly smaller.

In order to ensure that guppies thrive well under tank conditions, there is a need to mimic as much as possible their Amazonian habitat. You can achieve this ideal environment by focusing on the important water parameters.

Basic water chemistry

There are three important parameters that should be taken into consideration when creating ideal conditions for guppies. These parameters are water pH, temperature, and water hardness.


pH is a measure of acidity or alkalinity of a substance. It is measured on a scale of 1-14 with 7 being the neutral pH. Acidic pH refers to values which are lower than 7 while figures higher than 7 is alkaline or basic.

Ordinary tap water usually has a pH of 7. However, the water in your tank will have a different pH because of the chemicals that are dissolved or suspended in the water. Different species of fish thrive on different ph levels. For guppies, the idea water pH ranges from 6.8-7.8.

Water hardness

Although water hardness is an important water parameter for the growth and survival of your guppies, many aquarium owners often overlooked its significance. Fish thrive in a specific range of water hardness, and when these levels are not achieved, it can cause stress and possibly death.

Water hardness simply refers to the total dissolved minerals in the any type of water. Hard water is the term used when there is a high levels of dissolved minerals, while soft water has a low mineral level.

It is important that you appreciate the relationship that exists between your water pH and hardness. Hard water usually has high pH because the minerals present act as buffer thereby reducing the amount of acid (pH) in the water.

The ideal range of water hardness for guppies is GH 8-12.


Water temperature is equally important to your tank inhabitants. Fish and aquatic plants have been shown to tolerate only a limited range of water temperatures.

Another important factor that should be taken into consideration when talking about water temperature is consistency. Sudden and drastic changes in water temperature can often lead to health problems.

For Guppies, the ideal water temperature range is between 10-29 °C (50°F – 85°F); with guppy fry thriving best at 25.6 °C (78°F), juvenile 24.4 °C (76°F), and adults 23.3 °C (74°F).

About the Author:

Peter Hartono is the founder and CEO of Just Aquatic – a company based in Melbourne, Australia that provides a wide selection of live aquatic plants and aquarium decorations.

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