How Many Fish in a 29 Gallon Tank? – Detailed Answer

how many fish in a 29 gallon tank

Different fish tank sizes are available in the market, from a little 5-gallon tank up to a 300. A 29-gallon tank is considered a standard mid-size tank that is 30″ x 12″ x 18″.

For any new aquarists, one of the most urgent concerns is the number of fish the tank should accommodate. So, how many fish in a 29-gallon tank?”

Indeed, you may use the one inch of fish per gallon rule, meaning only about 29 inches of fish can be in a 29-gallon tank. However, this is only a general rule for some small fish.

Keep reading for detailed instructions and get more accurate answers!

How Many Fish Should You Put in a 29 Gallon Tank?


As overcrowding can cause fish to die, you also need to become a calculator to figure out how much space each fish needs.

When starting with a 29-gallon tank, the ideal fish type to add will include Molly Fish, Angelfish, Cory Catfish, and Fancy Goldfish.

1. The one-inch-per-gallon rule

Using 1 inch of fish for every gallon of water rule can calculate the number of fish in a 29-gallon fish tank.

Some others even use the rule, which is 1 cm of adult-size fish per litre of water.

A Molly Fish, for example, can reach 4 inches when they grow up. So ideally, a 29-gallon tank is just enough for five adult Mollies.

Generally, a 29-gallon fish tank can accommodate

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  • 3 fish of 6 inches – 8 inches long
  • 10 fish of 3 inches long
  • 12 fish of 2 inches long
  • 20 fish of 1 – 1.5 inches long


That’s the general rule, but there are more factors that impact the ideal number of fish.

2. Based on fish type

Indeed, larger fish require more space to swim around and breathe properly. Therefore, you can refer to the types of fish and their conditions and sizes necessary to get the right number of fish.

Some baby fish can have a tiny shape but turn out incredibly big when they grow up. Take the angle fish as an example, as they can grow up to 8 inches and require 10 – 15 gallons per fish.

You also need to pay attention to the characteristics of the fish you plan to add to your aquarium tank.

Territorial or semi-aggressive fish always require ample space. That means you may have to keep other fish less, or some fight will happen.

3. Based on type of tank

The type of tank also affects the number of fish you house. A 29-gallon fish tank is not always rectangular; some of them can be a cylinder or hexagon.

Different shapes of tanks may hold different amounts of fish, so let’s check out types of 29-gallon aquariums below.

Types of 29 Gallon Aquariums


1. Oceanic BioCube 29 Gallon

The 4-corners of Oceanic BioCube 29 Gallon are round edges for safety. This tank provides one of the complete aquarium systems with a list of items, including a hood, aquarium filter, and lighting.

Oceanic BioCube 29 Gallon also has Lunar LEDs integrated with a timer. The integrated filter also makes the maintenance process much easier if you’re a beginner. Therefore, the high-quality components allow you to comfortably keep saltwater or freshwater fish.

The Oceanic BioCube 29 Gallon seems to be a perfect size for those new to fish-keeping. It can accommodate 6 – 12 fish per BioCube tank of this size.

2. Aquarium Starter Kit 29 Gallon

Aquarium Starter Kit 29 Gallon is made of solid glass with LED lights and a top-notch filter. The filter works quietly and effectively, keeps the water clean, and prevents it from contaminating.

Meanwhile, the hoping hood makes feeding and cleaning easy. And, this tank kit is easy to set up and use, which perfectly suits beginners.

3. Coralife BioCube 29 Gallon

Coralife Biocube 29 is an excellent size for a medium-sized community of fish and plants with a cube shape. This tank is also ideal for most homes as not being so small that it prevents your fish and plants from swimming and growing inside.

The special design of the tank glass and hood makes it look sleek and beautiful.

Coralife Biocube 29 also comes complete with a lighting system. These smart LED lights are energy efficient that can shift from daylight to nightlight.

Maintenance will also be easy as Coralife Biocube 29 has an excellent wet/dry filtration system. Don’t forget to add more plants and accessories to make your fish tank look better.

Best Types of Fish for 29 Gallon Tank

The amount of fish you hold in a 29-gallon tank mostly depends on the fish type. Therefore, you should figure it out right after having a fish tank.

Here are some best fish suggestions for a 29 and 30-gallon tank.

You can also use this reference for a little bigger 36-gallon tank for a spacious swimming space for fish.

Fish Type Recommended number of fish in 29-gallon tank
Guppies (2 inches)12 – 15
Molly Fish (4 – 4.5 inches)4 – 6
Angelfish (6 – 8 inches)2 (as they are aggressive)
Goldfish (up to 12 inches)1
Neon Tetras (1.5 inches)16 – 18
Cory Catfish (2.5 inches)10 – 12
Cherry Barbs (2 inches)12 – 15

Size of fish as adult

Some fishkeepers, especially new ones, sometimes ignore the difference in size between baby fish and adult ones.

The size of baby fish may fit your aquarium, but what will happen if they grow up?

Let’s take goldfish, for example! Following the goldfish size chart, a one-month goldfish is only 1 inch, but an adult can get over 10 inches. Therefore, it can be the biggest fish you can put into a 29-gallon tank.

Your fish don’t have much space to swim due to overcrowding which can end up unhealthy and die.

To calculate the exact number of fish that can be kept in a 29-gallon tank, you also need to subtract the space for plants and decorations. There are so many things you need to find out!

Read more: List of the most favorite goldfish tank.

Cleaning and Maintenance of Fish Tank


Here are some simple steps you can follow in cleaning a fish tank!

  1. Prepare a bucket of tap water 10 – 12 hours before cleaning to naturally remove the chlorine.
  2. Wash your hands and arms in warm water (without using soap).
  3. Unplug the filter and lights then remove the decor and clean it with hot water
  4. Clean the glass with a glass scrub and use an algae scraper to get rid of the algae. Then, use a gravel vacuum to clean up any fish waste.
  5. Use the siphon to remove 10% of the water.
  6. Replace your decor in your tank, add the prepared water, and turn on your lights.
  7. You should monitor your tank right after cleaning to ensure everything works normally.

Going hand-in-hand with tank cleaning is the maintenance process. Maintenance is a mandatory process with any aquarium. It is not a difficult job that should be done weekly for such a tiny tank.

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  • During the maintenance process, partial water change (10-15%) can ensure fish stay healthy. Large water changes like 50% can sometimes cause fish stress and accidentally remove good bacteria simultaneously.
  • You must also pay close attention to ammonia and nitrate levels in your fish tank. The safety ammonia level is 0 ppm, while the nitrate levels range from 0 – 40 ppm.


What Fish Can Live Together in a 29-Gallon Tank?

Fishkeepers always love having various species of fish in their tank. But before adding any new fish, you need to ensure those combinations can get along and live peacefully together.

Here are some fish stocking combos that can fit in a 29-gallon tank and live peacefully with each other:

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  • 1 Bristlenose plecos + 2 Molly fish + 3 Cory Catfish
  • 2 Molly fish + 5 Neon tetras + 1 Platies
  • 2 Bristlenose plecos + 2 guppies + 5 cherry barbs
  • 3 Mollies + 2 Platies + 2 Guppies
  • 3 Cory catfish + 3 killifish + 5 neon tetras



Although the rule of thumb can help you determine how many fish in a 29 gallon tank, you also need to notice other factors to have an accurate answer. These factors include the type of your aquarium, fish type, size of adult fish, etc.

This article provides the necessary information for anyone with a 29-gallon aquarium. If you have any questions or suggestions, don’t hesitate to share them with us!