How Many Fish Can You Have In 29 Gallon Tank-This Much!

There are many different sizes of aquariums on the market; little 5 gallon tanks all the way up to 100+ gallon. Most of your glass fish tanks are going to be rectangular in shape, but if you search you can find hexagon, cylinder, or bow-front rectangular. If you purchase an acrylic tank, they are more easily formed into different shapes. So, how many fish can you fit in a tank? For today, we are going to focus on the 29 gallon tank.

How Many Fish Can You Have In 29 Gallon Tank? A 29 gallon tank is considered a mid-size tank. The tank is 30”x12”x18” and will weigh approximately 330 pounds when full of water. When deciding what fish and how many fish you want in your tank, use this rule; 1 inch long fish per 2 gallons of water.

So, depending on the fish you want, you have to take into consideration how big they will be as an adult fish. Most goldfish are about 3 inches when grown, so that would 3 gallons per goldfish. So you could have 4 goldfish in your 29 gallon aquarium.

There are other things that you need to take into consideration when purchasing fish for your tank. Take the goldfish for example; they are a bigger fish, bigger fish means more waste. So, I would only put 3 goldfish in a 29 gallon tank. A little less waste and a little more room for them to swim away. Sounds like a good idea to me. But please, feel free to have 4 in your tank if that is what you want.

We will go through a few different types of fish and how many you can have in your 29-gallon tank. We will also touch on filters, decorations, and different styles of 29-gallon tanks. By the end of our discussion, you will have a very good sense of how many fish you can have in your 29-gallon tank, and how to figure calculate it. 

Types of 29 Gallon Aquariums

If this is your first tank, congratulations! Becoming an aquarist is a great hobby and gives something spectacular for guests in your home to look at. Maybe you are just getting a tank so that your child(ren) can have their first pet. No matter why you are here, we are going to give you as much knowledge as we can on fish tanks. 

You have a few choices when purchasing your first tank, no matter what size you choose to go with. You can purchase a full aquarium kit, which will provide you with the basic items you need to set up your tank. Or, you can purchase the tank and all of the necessities separately. You also need to make sure you have a fairly quiet place picked out and that it is a big enough space for your tank and stand. 

If your plan is to have your tank for a long period of time and you know you want to keep more than 1 fish at all times, my suggestion is to spend a little extra and get the best tank you can.

Do not start with a small 5 or 10-gallon tank because then you will have to upgrade once your fish is fully grown. In the end, that is going to cost you more than just purchasing a bigger tank, to begin with. Then you have the option of 1 fish or 5 or 6 fish, depending on the species.

Most of your 29 gallon tanks are going to be rectangular in shape, unless you purchase an acrylic tank. Here are my top 3 recommendations for complete 29 gallon tanks.

01)-Oceanic BioCube 29 Gallon: the corners of this tank are curved, offering a very appealing look. So, it is more of a rounded cube shape. Different, but very pleasant to look at. It has Lunar LEDs that will make your decor look amazing.

Your maintenance is going to be easy because of the integrated filter. There are also 2 fans in the hood of this tank and it has a timer for the lights. Your tank lights should be set for intervals of 12 hours. This tank, in my opinion, is perfect for beginners. I cannot find it on Amazon, I cannot find it on Amazon, you can check the brand website.
02)-Aquarium Starter Kit 29 Gallon: this setup includes the tank, the LED lights, and the filter. There are also a couple of bonus accessories included as well. The openings in the hood allow the feeding to be simple and easy. The hood is also a low profile hood, so you can put the tank in a smaller space if needed. You get to choose the decor that you want to make the tank your own and fabulous. Check Aquarium Starter Kit 29 Gallon on Amazon here.
03)-Coralife BioCube 29 Gallon: I am absolutely in love with these cube-shaped tanks. It almost makes things look 3-D. They are more appealing than the traditional rectangle tank. Each fluorescent light on this tank has its own cord, so you can control how much light is on throughout the day. It also includes cooling fans and a very quiet filter.

You could feasibly put this in a bedroom and the noise isn’t going to keep anyone awake or interrupt their sleep. Choose your own plants and another decor to fully bring this aquarium to life. Check Coralife BioCube 29 Gallon on Amazon here. 

Remember, when buying your tanks, the kits are going to be more affordable. The only items you should have to purchase separately are the decor items that you want in your tank. Otherwise; the kit will come with the tank, hood, lights, and maybe a heater.

Some will also include bonus items like nets. If you purchase everything separately, you will spend way more money. But that is something that you can decide as well. If you want the top of the line, everything, in your tank then I say; go for it! 

**TIP** Take into account the fish you are wanting for your tank, while you are shopping. Some fish have specific requirements when it comes to lights and water temperature.

Best Types of Fish For Your 29 Gallon Tank

Some say you can have 20 fish in a 29-gallon fish tank. Personally, I think that that is too many. You also need to take the plants and other decorations into consideration. 20 fish with plants, rocks, driftwood, etc.. and your fish are not going to have any space to swim. They are going to get cranky, they will end up unhealthy, and then you may lose ½ of them because your tank is overcrowded.

I would suggest 3-5 fish in a 29-gallon tank, depending on the species of fish and what plants and décor you have. Others say that 8-12 fish is perfect for this size of a tank.  There a just a couple of aspects that you need to pay close attention to: 

  • The temperament of fish; you do not want fish who is going to bully or fight
  • Size of fish as adults; more babies will fit, but what happens when they are grown? You have to upgrade the tank, which means spending more money.
  • You want plenty of room for the tank equipment, decorations, and for the fish to comfortably swim around.

Some fish you can keep in a 29-gallon tank are; guppies, mollies, neon rainbowfish, certain catfish, and many others. As always, research and ask tons of questions. You want to make sure that your fish are going to be happy and healthy because, in the long run, it will save you money.

Guppy fish

Guppies: if you are a beginner they suggest 5 gallons of water per 1 inch of fish. Just until you get the feel of taking care of the fish, maintaining the tank, and testing the water.

After you are comfortable and confident, you can add a few more. So, with 5 gallons per inch of fish in a 29 gallon tank, you can have 5-6 guppies to start with.

Once you are more experienced, you can calculate 2 gallons of water per inch of fish so you could actually have 14 guppies in your 29-gallon tank. You want to make sure, with the decorations that they still have plenty of space to swim. So just to be on the cautious side, I would personally only have 10 guppies in my tank. A happy medium!

So that would allow you to have 5-6 of the rainbow fish in your 29-gallon tank. I feel, just to be on the safe side so that they have plenty of swimming space I would have 4 of the neon rainbow fish. I like to err on the side of caution. 

Goldfish: because goldfish can get bigger, you are not going to be able to have many of them, unless you go for a much bigger tank. The common goldfish need 20 gallons of water.

If you choose a “fancy” goldfish, which are a little bit smaller, they need 10 gallons per fish. So, going by those stats, you can only have 1 common goldfish in your tank or 2 fancy goldfish. But, you can also put in 3-4 other small fish (like the guppies).

Make sure you do similar research on the fish you are wanting to put in your tank. They need room to grow and swim, comfortably. Don’t forget to take into account your decor, hence why I took a fish (or 2) away in the above equations. It is better to be cautious than to lose your fish because of overcrowding or health issues. 

Maintenance for 29 Gallon Tank

As with any size of fish tank, maintenance is mandatory. It is fairly simple to do and should be done on a regular basis, normally once a month. You can do a few small tasks everyday that will make the monthly maintenance even more simple, but that is up to you.

There are also certain factors that will determine how often you should clean your tank; the size, number of fish, size of fish, Coldwater or heated tank, fresh or saltwater tank, and type of filter.

Partial water changes are essential no matter the factors above. This will maintain the health of your fish. The best place to start is with 10-15% water changes. Some say that you should change 25%, others say that that is too much at once and causes too much stress on the fish. It also removes too much of the ‘good bacteria’ that is in your tank. So, 10-15% it is!

Tank Cleaning Process

Here are the basic steps for cleaning your aquarium:

  • Make sure you set out a bucket of tap water the night before. This allows the chlorine to evaporate and the water to reach room temperature (which will be closer to your tank temperature).
  • Wash your hands with hot tap water, no soap! The soap or other chemicals that may be on your hands can harm your fish. 
  • Use an algae scraper to remove algae from the inside glass and any decorations (if you do this once a week, it will speed up the cleaning process)
  • Siphon out the 10-15% that is recommended, but DO NOT get rid of it.
  • Vacuum the gravel to clean up any fish waste and leftover food. Go very slowly so that you do not frighten the fish too much
  • Use the tank water that you siphoned to clean your filters and filter mediums. This allows you to keep most of the beneficial bacteria that help keep your tank healthy
  • Once you clean the filter and the medium (or change it) you are done. But the clean tap water that has sat out overnight into the tank. 

Cleaning Your Filter and Medium

This is going to depend on which type of filter you use in your tank. There are 3 primary filters; mechanical, biological, and chemical. Some filters will have re-usable mediums that you will have to clean when you clean your tank. Other filters will have disposable mediums, and you just put in a new one during your monthly maintenance. 

With the mechanical filter you will need to change your sponge or foam pad once a month. DO NOT do the filter change and the partial water change at the same time. You do not want to completely shock your fish with 2 changes at once. Take just a little water from the tank and swish your filter around in it to remove most of the gunk. 

If you have a chemical filer, such as carbon, it should be changed every 3-4 weeks. You can do this filter change and your partial water change at the same time and your fish will be ok. If your water becomes cloudy fairly quickly then you may want to change the filter every 2 weeks.

Biological filters do not need to be changed very often at all. When you do change them make sure to do your partial water change at the same time and use the old water to clean the filter. You do not want to lose the healthy bacteria.

For smaller, 5-10 gallon tanks, it is recommended that you clean them once a week. The smaller the tank the quicker the buildup of ammonia and other harmful substances. The tank water is the air for your fish and you want to keep it as clean as possible.

With the mid-sized, 29 gallon and up, you should clean it every other week and anything over 50 gallons you can clean once a month. Of course all of that depends on how many fish you have in the tank, the types of plants (whether they are live or rubber) and how much your fish are excreting and not eating.

You want to make sure you have a test kit, so that you can test your chemical levels once a month. Keep an eye on your fish when you turn on the light, feed them, turn off the light, and throughout the day. If anything looks abnormal then test the water immediately. 

If you want to upgrade your filter, you can choose one that has an indicator light that will flash when the filter is needing to be changed. This is an added benefit for those that are extremely busy with work, maybe travel out of town, or just have so much going on that they do not want to forget when to change the filter.


Depending on the species of fish depends on how many you can have in a 29-gallon tank. Make sure when you start looking at everything and preparing to purchase that you follow the rule that was listed in the beginning; if you are new to aquariums then you want 5 gallons for every inch of fish.

If you are more experienced or feel very comfortable and confident in your ability to handle everything, then you can go with the 2 gallons of water for every inch of fish. Remember to also account for the plants and decorations that you have in the tank, and if you are going to do more than 1 species, research!! Make sure they are going to be able to cohabitate without any bullying or fighting.


I'm passionate about fish pets and love sharing everything I learn about them.

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