Small Spaces, Happy Swimmers: How Many Fish Can Be in a 3-Gallon Tank?

clear glass fish tank with blue fish


Aquariums can be a wonderful addition to any living space, offering a peaceful and fascinating glimpse into the underwater world. However, not everyone has the space or resources for a large aquarium, leading many to opt for smaller tanks instead. One common question that arises when setting up a small tank, such as a 3-gallon aquarium, is how many fish can comfortably live in such a limited space. In this blog post, we’ll discuss the factors to consider when stocking a 3-gallon tank and offer recommendations for selecting the right fish to thrive in a small environment.

Factors to Consider When Stocking a 3-Gallon Tank

  1. Fish Size: Smaller fish species are better suited for a 3-gallon tank due to their reduced need for swimming space and lower bioload, which is the amount of waste they produce.
  2. Fish Temperament: Peaceful fish that can coexist without aggression are ideal for small tanks, as territorial or aggressive behavior can cause stress and harm in confined spaces.
  3. Water Quality: Smaller tanks can be more challenging to maintain in terms of water quality, as toxins and waste can accumulate more rapidly than in larger tanks. Therefore, it’s essential to avoid overstocking a 3-gallon tank to minimize the risk of water quality issues.

Recommended Fish for a 3-Gallon Tank

Considering the factors mentioned above, here are some fish species that could potentially thrive in a 3-gallon tank:

  1. Betta Fish: A single betta fish can live comfortably in a 3-gallon tank. They are relatively hardy and can tolerate a variety of water conditions. However, they should not be kept with other fish in such a small space, as they can be territorial and aggressive towards tankmates.
  2. Micro Rasboras: Species such as the Chili Rasbora or the Exclamation Point Rasbora are tiny schooling fish that can be kept in small groups in a 3-gallon tank. A group of 3-4 of these fish should be manageable, but keep in mind that water quality must be diligently maintained.
  3. Endler’s Livebearers: These small, colorful fish are similar in appearance to guppies but are better suited for a 3-gallon tank due to their smaller size. A small group of 3-4 Endler’s Livebearers could potentially be housed in a 3-gallon tank, but care should be taken to ensure proper water quality.
  4. Shrimp and Snails: Although not technically fish, small invertebrates like cherry shrimp or nerite snails can be a great addition to a 3-gallon tank. They have a minimal bioload and can help control algae growth.

Important Note: It’s crucial to research the specific needs and compatibility of any species you plan to keep in your 3-gallon tank. Some fish may have unique requirements that make them unsuitable for such a small space, even if they are small in size.


A 3-gallon tank may be small, but with careful planning and attention to water quality, it can still provide a comfortable home for a select few fish species. It’s essential to choose small, peaceful fish that can coexist without issue and monitor water conditions closely to ensure a healthy environment for your aquatic pets. With patience and dedication, a small tank can be transformed into a thriving ecosystem and a captivating addition to your living space.