Skip to content Skip to sidebar Skip to footer

Best Fish for 3 And 3.5 Gallon Tanks

Best Fish for 3 And 3.5 Gallon Tanks

If you have a 3-gallon tank or a 3.5-gallon tank, then you probably have some idea of the limits of using such a tiny amount of water to house your tropical fish. Compared to a bigger tank, small tanks can be challenging to stock with fish that will be happy and healthy in such a small space.

However, if you take the time to do your research and select the ideal fish for your aquarium, you can create a beautiful and thriving aquarium. In this article, we'll provide recommendations on the best fish for 3 and 3.5-gallon tanks and some stocking tips to help you along the way!

Stocking Tips For Smaller Tanks

With some advance planning, stocking more small aquaria can involve more preparation than selecting fish for larger ones. Previously we published an article on aquascaping tips for smaller tanks, but learning how to stock them is equally crucial. Here are some things to bear in mind.

Know The Rules Of Thumb

Rules regarding stocking a tank shouldn't be applied to your nano aquarium without considering that other factors, such as the nitrate and pH levels of your water, the filter you have, etc., can affect the health of the fish. But they're an excellent starting point if you're just beginning to maintain or keep nano aquariums.

Generally, you can keep an inch of fish per gallon of water in most fish tanks. This means that a 3-gallon tank can house up to 3 inches of fish, and a 3.5-gallon tank can accommodate up to 3.7 inches of fish. When it comes to shrimp, you can keep about 10 shrimp per gallon of water. However, this assumes that you have a well-cycled tank. If you're starting from scratch, it's best to wait for it to circulate for a few days.

Consider Using A Smaller Tank For Specific Purposes

Just because you have a 3 or 3.5-gallon aquarium doesn't mean it has to be devoted to your fish as a permanent dwelling. In some cases, it makes more sense to use the smaller tanks as breeding tanks and fry grow-out tanks rather than holding habitats for adult fish.

These small aquariums also make good quarantine tanks for new fish. You can use them to hold sick or injured fish until they recover. When you quarantine fresh or sick fish in a separate fish tank, you can provide them with the care they need knowing it won't affect your main fish tank's water quality.

Maintain Excellent Water Conditions

Among the most essential points to remember when storing a small fish tank is maintaining safe and correct water conditions. Even a tiny change in the water level parameters in a smaller tank can quickly result in fish stress and death. Maintain safe levels of ammonia and nitrates in fish tanks by performing regular water changes.

Moreover, counsel having an appropriately sized filter is essential. Filters that are too large can make it tough to do routine inspections on your tank. However, too slim filters will not allow adequate filtration for your tank. Below are some of our best filter suggestions for the number of people in your tank.

15 Best Fish for 3 And 3.5 Gallon Tanks

We will review some stocking guidelines for 3-gallon and smaller fish tanks.

1. Guppies


The guppy is a small, tropical fish that can easily be kept in a home aquarium. Guppies are among the most common aquarium fish for their brightly colored patterns and darting movements. They are also relatively easy to breed and provide colorful eggs that can be hatched into young fish.

Regarded as among the challenging fish to keep in captivity, guppies are very well accommodated in small tanks of 3 gallons or less. Little guppies also are pretty peaceful to watch as they swim about their chosen tank, and their flashy bodies will add a vibrant splash of color to your aquarium. Fancy guppies come in various colors, giving birth to several decorative aquatic species.

One of the safest fish for beginners, guppies do well in a wide range of freshwater conditions and tolerate a slightly alkaline pH level. This is why these little, brightly colored fish are so beloved among aquarium hobbyists!

2. Endler’s Livebearers

Endler’s Livebearers

Endler s livebearers are a family of fish known for their hardiness and fecundity. This family includes fish like goldfish, albino cichlids, and dwarf gouramis. The Endler's livebearer is a popular fish in the home aquarium market because they are easy to care for and can be kept relatively small. These fish have a moderate size range, so they can be found in stores in tiny tanks up to 14 gallons.

Some endlers are mistakenly considered guppies due to their size and shape, but they're actually a bit more aggressive. They don't harm your tank, but they are noisy and active fish that will continuously swim near the top. They come in various colors, including red, orange, green, yellow, and blue-grey.

Endler's livebearers are one of the most accessible types of fish to breed, making them an excellent option for beginning fish keepers. Overpopulation could become a concern without proper tank size, so be sure to provide plenty of containing places for nursing moms and half-secluded tanks for fry.

3. Cherry Shrimp

Cherry Shrimp

Since they are not technically fish, Cherries Shrimp are an excellent addition to any small tank. Unlike more active species, these little invertebrates are peaceful and will not attack or harm your other fish. They're frequently the preferred choice of betta fish and other species found timidly.

Cherry shrimp can usually be used for algae and decaying plant matter consumption. They can be found in various colors, such as red, orange, yellow, green, and blue. You may maintain a small school of cherry shrimp in your 3 or 3.5-gallon tank or add a few as a colorful supplement.

4. Ember Tetras

Ember Tetras

Ember tetras are an excellent alternative for a small bowl. They are lively and active fish, making them a lot of fun to watch. They are sturdy fish, too, making them an outstanding option for beginners.

Ember tetras can be found in various color combinations, including red, yellow, blue, and green. Their bodies are transparent, so you can see their organs swimming around their tank. Ember tetras are a peaceful type of fish that will harmoniously coexist with other small species.

5. Chili Rasboras

Chili Rasboras

If you want the fun of a larger fish tank, but don't have the space for a full-size community tank, look no further than chili rasboras. These friendly fish come in various vibrant colors and are more active than most of their counterparts. They are hardy fish that Riviera house is fond of.

Chili rasboras are schooling species of freshwater fish. Therefore, you must keep at least six of them in your tank. They thrive in planted aquariums with lots of hiding places and areas for swimming. Try to maintain a stable water temperature of around 75 degrees F to help them remain healthy and active.

6. Zebra Danios

Zebra Danios

The zebra danio is one of the lowest-maintenance nano fish for a 3-gallon fish tank. These hardy little fish will acclimate to a wide range of water conditions, are incredibly active swimmers, and come in black and white.

Zebra danios are schooling fish that will thrive in properly planted tanks with plenty of plants and space for exercise. They're peaceful fish that will likely get along with other small fish. You can keep a collection for your 3-gallon tank without overcrowding.

7. White Cloud Mountain Minnows

White Cloud Mountain Minnows

The cloudless white-spotted minnow is one of the most distinct microalgal fish for small tanks. These active fish thrive in planted tanks with lots of artificial plants and plenty of space to run around. They are peaceful fish that get along well with other microalgal fish.

White-cloud minnows are hardy fish that thrive when exposed to various water conditions, from temperatures between 64 and 76 degrees and pH ranges of 6.0 to 8.0. They are generally easy to care for, though regular water changes are advisable.

8. Otocinclus


If you're looking for a diminutive filter feeder to hide in your nano tank, think about an otociclus or otociclus catfish. These fish have small bodies and resemble a cross between a catfish and a suckerfish.

Otocinclus are primarily herbivorous fish that will do best in tanks with plenty of live plants. A diet consisting of algae wafers and boiled vegetables will keep them happy and well-nourished. They can tolerate a wide range of water conditions but prefer water parameters between 68 and 78 degrees F and a pH of 6.5 to 7.5.

9. Neon Tetras

Neon Tetras

Neon tetras are one of the most famous fish in aquarium culture. These robust fish have attractive coloring and life-like movements that make any room come alive. They come in various colors, including blue neon tetras, red neon tetras, green neon tetras, and albino neon tetras.

Neon tetras are quiet fish that tend not to need much swimming space. These are an excellent choice for beginning fishkeepers, but it is advisable to purchase a heater as their ideal temperature range is 74 to 82 degrees Fahrenheit.

10. Betta Fish

Betta Fish

Betta Splendens, also known as the Siamese fighting fish, are frequently considered solitary fish because of their aggressive character in the wild. However, domesticated bettas can be kept in small groups without issue as long as there is plenty of space for each fish. Male bettas typically have more vivid coloring than females and are sought-after for their attractive fins.

Betta fish have ample swimming space, so a 3.5-gallon tank is usually the smallest recommended size. Many parents choose the betta as the first pet fish for kids because they forgive first-timer mistakes. Try adding one of these betta-friendly plants to your tank to ensure they are happy!

11. Least Killifish

Least Killifish

Least Killifish or Heterandria Formosa is one of the tiniest fish in the world. Because of their tight dimensions, they're utilized as feeder fish rather than kept in aquariums. Nonetheless, they're a good alternative for a 3-gallon tank since they thrive in confined spaces.

These little guys belong to a pond-dwelling family of fish known as livebearers, characterized by their production of live young instead of eggs. Compared to other members in this family, the least killifish is non-annual and can even survive for six years!

12. Asian Stone Catfish

Asian Stone Catfish

Another popular fish in hobby circles is the Asian catfish. These bottom dwellers are safe creatures that do well in tanks with plenty of hiding places. And aquarium plants. They are not particularly active swimmers, so they're an excellent choice for those who want a low-maintenance animal.

Asian stone catfish can reach a maximum length of 3 inches, so a 3-gallon cage is a minimum dimension suggested. Ensure the aquarium is densely covered o the fish feel safe and secure.

13. Pygmy Gourami

Pygmy Gourami

Pygmy gouramis are some of the most energetic freshwater fish around, making them a popular option for people who want to explore active fish. This peaceful fish should not be housed with more extensive or less sturdy fish. They do well in large aquaria and even have good compatibility with bettas!

These fish are tiny, generally 1 to 3 inches long. They tend to construct nests out of bubbles. They're often housed in 3-gallon tanks.

14. Pea Puffer Fish

Pea Puffer Fish

Most types of beginner fish have been mentioned already, but we would be remiss to exclude the Pufferfish! These small fish gain their name due to their natural propensity to enlarge themselves to appear larger than they actually are. They're an incredibly striking neon green color and add a fun element of movement to your tank.

Advanced aquarists keeping pea puffers need to observe that this fish is more challenging to care for than other species. It's susceptible to medication and plants, so your tank must stay clear of chemical residue.

15. Bumblebee Goby

Bumblebee Goby

Among the abundance of fish options on this page, the Bumblebee Goby is one of the most distinctive. These fish earn their name from their black and orange stripes, reminiscent of a bumblebee. They are a shy species best suited for keeping in smaller groups.

Bumblebee gobies can grow up to four inches in length, making them an asset if you have a little tank. Make sure to keep up maintenance so that your tank has healthy fish.

Tips For Fish Selection: Things To Avoid

Our list of fish was an excellent place to consider for anyone seeking an alternative to 3-gallon tank inhabitants. While you can feel free to choose from a wide-ranging assortment of options, you should avoid a few variables to guarantee the success of your aquarium.

Avoid Large-Bodied Fish Species

Larger fish require more room, so it's wiser not to include them in your tank if you have a smaller one. Larger fish may also jump out of the container, which can be dangerous if you have pets or children.

Bigger fish also produce more waste, and that waste makes balancing the water parameters harder. Be sure to never keep fish any longer than 2 inches to mitigate dangerous ammonia and nitrite levels.

Avoid Aggressive Fish Species

Aggressive behavior can be incredibly detrimental on a small pond, not necessarily on a big pond. This is because territorial fish will strive over members of their type to assert dominance and construct a location for themselves using the energy. Disputes can easily be avoided in a bigger pond since fish have more area. These individual clashes in a small tank may result in severe injury or death.

Even tiny fish, such as the harlequin rasbora, can become aggressive if they don't have enough space to survive independently. It, therefore, is essential to shy away from aggressive fish and never to pick out just their size when thinking about which fish to buy for your community.

Keep Fish in Quantities That Are Appropriate for the Tank

Selecting one species of fish for the 3-gallon tank is probably not sufficient. Because small tanks are less stable than more significant habitats, it's essential to ensure that you have more than one occupant so the new fish can find a better education.

2-3 small schooling fish of the same species can help maintain the water parameters in the tank and ensure its healthy environment. That way, you will be able to keep enjoying your company with several different fish without worrying about any abuse that may happen if they don't have adequate space to adapt.

Fish Species To Avoid

At this point, you should understand the rules of thumb you should follow when stocking a nano tank. While discussing various fish selection tips earlier, there are still different fish species that often end up in smaller enclosures than what they require. This leads to the death of a sad fish as a direct result.

Here are a few examples of fish that should not be kept in a three-gallon tank.

1. Goldfish

Goldfish are beautiful and straightforward to take care of, making them a good alternative for beginners. However, they require much more than a bowl or a three-gallon tank! They will need a pond or a 20-gallon tank to thrive. That way, you'll discover why goldfish should not be kept in a bowl.

2. Tiger Barbs

Tiger barbs are a popular community fish for community tanks, but they find it difficult to reproduce in small tanks. These active fish need much swimming space and will become anxious in a minimal environment.

3. Rainbowfish

Rainbow perch are a popular choice for those who want to have a vibrant fish but also need a lot of space. These fish can develop up to 3 inches long and should be kept in a large tank with at least 10 gallons of water.

4. Platies

A peaceful fish, platies are suited for a community tank. However, they can grow up to 2 inches long and should be housed in a tank at least 10 gallons in size. This will allow the platies enough space to swim and avoid aggressive behaviors from other fish.

5. Cory Catfish

Cory catfish are a preferred option for small tanks because they are small and docile. However, they must not be kept in an enclosure with less than 5 gallons of water because they must adapt to the schooling requirements of another fish.


After reading our article on the best fish for smaller tanks, we hope you know to steer clear of adding new fish to your tank whenever possible and use this information as a general guideline. Adhering to all these guidelines can create a healthy and vibrant ecosystem in your nano tank!

Did you find this post helpful? Don't forget to share it with your friends! And if you have managed to stock your own small tank, be sure to let us know in the comment section below. We enjoy hearing from our readers!

Post a Comment for "Best Fish for 3 And 3.5 Gallon Tanks"