how big is a 5 gallon fish tank, The Ultimate Size Guide

Discover the perfect size for your aquatic friends with our guide on the dimensions of a 5 gallon fish tank. Learn about tank dimensions and choose the ideal habitat for your underwater buddies.

how big is a 5 gallon fish tank

Welcome to the world of fishkeeping and aquariums! If you’re considering setting up a 5-gallon fish tank or just curious about its size, you’re in the right place. In this informative and conversational blog post, we’ll explore the dimensions of a 5-gallon fish tank, discuss why choosing the right size tank is crucial, and delve into various aspects of fish care and tank maintenance. So, let’s dive right in!

What is a 5 Gallon Fish Tank?

First things first, let’s clarify what exactly a 5-gallon fish tank is. A 5-gallon fish tank, as the name suggests, holds approximately 5 gallons (or 18.9 liters) of water. This compact aquarium is a popular choice among beginners and seasoned fishkeepers alike due to its manageable size and versatility.

Why is it Important to Choose the Right Size Fish Tank?

Selecting the appropriate tank size is a critical decision in the world of fishkeeping. The size of your tank directly impacts the health and well-being of your aquatic pets. A 5-gallon fish tank is considered small to medium-sized, and understanding its dimensions will help you make an informed choice for your aquatic friends.

How to Measure a Fish Tank

Before we dive deeper into the specifics of a 5-gallon tank, let’s briefly go over how to measure one. Fish tanks are typically measured in gallons (or liters), and the measurement refers to the amount of water the tank can hold when filled to capacity. To measure the size accurately, consider both the tank’s physical dimensions and its water volume.

The Benefits of Having a 5 Gallon Fish Tank

Before we get into the nitty-gritty details, let’s talk about the advantages of choosing a 5-gallon fish tank:

  • Manageability: Smaller tanks are easier to set up and maintain, making them perfect for beginners.
  • Space-Saving: Ideal for those with limited space, such as apartments or offices.
  • Cost-Effective: Generally more affordable than larger tanks, both in terms of equipment and ongoing expenses.
  • Versatility: While limited in size, a 5-gallon tank can still house a variety of beautiful fish and aquatic plants.

Now that we’ve covered the basics, let’s move on to understanding the standard dimensions of a 5-gallon fish tank.

Standard Dimensions of a 5 Gallon Fish Tank

A standard 5-gallon fish tank typically has the following dimensions:

  • Length: Approximately 16 inches (40.6 cm)
  • Width: About 8 inches (20.3 cm)
  • Height: Roughly 10 inches (25.4 cm)

These dimensions may vary slightly depending on the manufacturer, so it’s essential to check the specific measurements when purchasing a tank. The shape of your tank can also vary, with rectangular and cube-shaped tanks being the most common.

Different Shapes of 5 Gallon Fish Tanks

While the standard rectangular tank is the most prevalent, 5-gallon tanks come in various shapes to suit your preferences and available space. Here are a few popular options:

  • Rectangular Tanks: These are the most common and offer a good amount of swimming space for your fish.
  • Cube Tanks: Cube-shaped tanks provide a unique and compact design, making them an excellent choice for a desktop or countertop.
  • Bowfront Tanks: These tanks have a curved front panel, adding a touch of elegance to your setup.

When choosing a tank shape, consider both aesthetics and the comfort of your fish. Rectangular tanks often offer more swimming space, while cube and bowfront tanks may enhance the visual appeal of your aquarium.

How to Choose the Right Size Fish Tank for Your Needs

Selecting the right tank size is a crucial step in creating a thriving aquarium. Here are some factors to consider when choosing the size of your fish tank:

1. Number and Type of Fish

Different fish species have varying space requirements. Some fish are small and can thrive in a 5-gallon tank, while others need more room to swim and grow. Research the specific fish you plan to keep to ensure they are suitable for a 5-gallon habitat.

2. Available Space

Consider where you plan to place your aquarium. A 5-gallon tank fits well on most tabletops, counters, or sturdy shelves. Measure the available space to ensure a proper fit and easy access for maintenance.

3. Budget

Smaller tanks are generally more budget-friendly. Keep in mind that while the initial cost may be lower, you’ll still need to invest in equipment like a filter, heater (if necessary), lighting, and decorations.

4. Maintenance Commitment

Smaller tanks require more frequent maintenance because changes in water quality can happen quickly. Ensure you have the time and commitment to perform regular water changes and monitor your fish’s health.

The Best Fish for a 5 Gallon Tank

Now that you’re acquainted with the dimensions and considerations for a 5-gallon fish tank, let’s talk about the best fish species for this size of aquarium. Here are some popular options:

Betta Fish (Betta splendens)

Betta fish, also known as Siamese fighting fish, are a favorite choice for 5-gallon tanks. Their vibrant colors and flowing fins make them stunning to look at, and they are relatively low-maintenance.

Dwarf Gourami (Trichogaster lalius)

Dwarf gouramis are small, peaceful fish with striking colors and patterns. They adapt well to smaller tanks and can coexist with other peaceful fish species.

White Cloud Mountain Minnow (Tanichthys albonubes)

These small, active fish thrive in cool water and are an excellent choice for unheated 5-gallon tanks. They are social and do well in groups.

Endler’s Livebearer (Poecilia wingei)

Endler’s livebearers are tiny, colorful fish that are perfect for small aquariums. They are active swimmers and can be kept in groups.

These are just a few examples of fish that can thrive in a 5-gallon tank. Always research the specific care requirements of the fish you choose to ensure they are compatible with your tank size.

How Many Fish Can I Keep in a 5 Gallon Tank?

One common question among fishkeepers is, “How many fish can I keep in a 5-gallon tank?” While it’s tempting to fill your tank with a variety of fish, it’s essential to consider the size and behavior of your chosen species. Overcrowding can lead to stress, aggression, and poor water quality. As a general guideline:

  • For small fish like bettas, a single fish is suitable for a 5-gallon tank.
  • If you choose smaller schooling fish, you can typically keep 2-3 individuals, but always check species-specific recommendations.
  • Avoid keeping large or aggressive fish in a 5-gallon tank, as they may become territorial and harm other fish.

Remember that less is often more when it comes to maintaining a healthy and harmonious aquarium.

How to Set Up a 5 Gallon Fish Tank

Setting up a 5-gallon fish tank is an exciting process that involves creating a suitable environment for your aquatic pets. Here are the basic steps to get you started:

1. Gather Equipment:

  • Tank: Purchase a 5-gallon aquarium with a secure lid.
  • Filter: Choose a filter appropriate for your tank size to maintain water quality.
  • Heater (if needed): If you plan to keep tropical fish, a heater will maintain a stable temperature.
  • Substrate: Select an aquarium substrate like gravel or sand.
  • Decorations: Add decorations and plants for aesthetics and fish enrichment.
  • Water Conditioner: Use a water conditioner to treat tap water and make it safe for your fish.
  • Thermometer: Install a thermometer to monitor water temperature.
  • Lighting: If your tank doesn’t come with built-in lighting, consider a suitable aquarium light.

2. Set Up the Tank:

  • Rinse the substrate and decorations before adding them to the tank.
  • Fill the tank with dechlorinated water to the desired level.
  • Install the filter, heater (if necessary), and thermometer.
  • Add plants and decorations, creating hiding spots and swimming areas for your fish.
  • Cycle the tank by running the filter for a few weeks to establish beneficial bacteria and ensure a stable environment.

3. Introduce Fish:

  • After cycling the tank, introduce your chosen fish gradually.
  • Acclimate them to the water temperature and conditions by floating their bag in the tank for about 20-30 minutes.
  • Release the fish into the tank gently.

4. Maintain the Tank:

  • Perform regular water tests to monitor ammonia, nitrite, and nitrate levels.
  • Conduct weekly water changes (about 20-25% of the water) to maintain water quality.
  • Feed your fish a balanced diet and remove any uneaten food promptly.

How to Maintain a 5 Gallon Fish Tank

Maintaining a 5-gallon fish tank is an ongoing commitment to ensure your fish thrive. Here are some essential maintenance tasks:

  • Regular Water Changes: As mentioned earlier, perform weekly water changes to remove toxins and maintain water quality. Use a siphon to vacuum the substrate and remove debris.
  • Filter Maintenance: Clean or replace filter media as needed to prevent clogs and maintain efficient filtration.
  • Monitor Temperature: Ensure the water temperature remains within the optimal range for your fish species.
  • Feeding: Feed your fish an appropriate diet, and avoid overfeeding, as excess food can lead to water quality issues.
  • Trim Plants: If you have live plants, trim them as they grow to prevent overcrowding and maintain a balanced ecosystem.
  • Observe Fish Behavior: Keep an eye on your fish for any signs of illness or stress, and take action promptly if needed.

You May Also Like:


In conclusion, a 5-gallon fish tank offers a compact and manageable way to enjoy the beauty and tranquility of an aquarium in your home or office. Understanding its dimensions and the factors involved in selecting the right tank size is crucial for the well-being of your aquatic pets.