How Many Neon Tetra Can Be in a 40-gallon Tank

How Many Neon Tetra Can Be in a 40-gallon Tank?

Key Takeaways

Here’s a quick reference guide on how many Neon Tetra can be comfortably kept in a 40-gallon tank:

Tank Size40-gallon
Neon Tetra26 to 30 (approximate)
Water pH6.0 to 7.8
Water Temperature72°F to 82°F (22°C to 28°C)
PlantsLive plants, floating plants
SubstrateSoft substrate
Tank MatesPeaceful fish compatible
LightingDimly lit tank

If you’re an avid aquarium enthusiast or a beginner looking to start your aquatic hobby, Neon Tetra is a popular choice. These vibrant and peaceful fish are known for their stunning colors and playful behavior.

However, when it comes to setting up their habitat, one question often pops up: how many Neon Tetra can be housed in a 40-gallon tank?

Ideal Neon Tetra Environment

Before we dive into the numbers, let’s take a quick look at the ideal environment for Neon Tetras. These small, schooling fish thrive in a well-maintained aquarium with suitable water conditions.

They prefer slightly acidic to neutral water with a pH range of 6.0 to 7.8 and a temperature between 72°F and 82°F (22°C to 28°C).

To recreate their natural habitat, it’s essential to include live plants, soft substrate, and plenty of hiding places using driftwood or rocks. Neon Tetras are also known to enjoy a dimly lit tank, so consider adding floating plants or low-intensity lighting.

Now that we have the basics covered, let’s delve into the question of how many Neon Tetra can be comfortably housed in a 40-gallon tank.

Calculating the Number of Neon Tetra

When determining the number of fish suitable for your tank, it’s crucial to consider the fish’s adult size, behavior, and the tank’s capacity. Neon Tetras are small, typically reaching a maximum size of about 1.5 inches (4 cm) in length. They are also known as schooling fish, meaning they prefer to be in groups of at least six to eight individuals.

A general rule of thumb is to allocate 1 gallon of water per inch of fish. Based on this guideline, a 40-gallon tank could accommodate approximately 26 to 30 Neon Tetras.

However, it’s important to remember that this is a rough estimate, and other factors such as filtration, additional tank occupants, and the specific needs of your fish may require adjustments to the stocking level.

To ensure a healthy and stress-free environment, maintain good water quality by performing regular water changes and keep an eye on the behavior and compatibility of tank mates.

Remember that overcrowding can lead to poor water quality, stress, and potential health issues for your fish.


Neon Tetras are a beautiful addition to any aquarium, known for their lively colors and sociable nature. In a 40-gallon tank, you can comfortably house around 26 to 30 Neon Tetra, keeping in mind the necessary water conditions and suitable tank mates.

Remember, while these numbers provide a rough estimate, the well-being of your fish should always be the top priority.

By maintaining good water quality, providing a stimulating environment, and monitoring their behavior, you’ll ensure a thriving community of happy Neon Tetras in your 40-gallon tank. Happy fish keeping!