Best 20 Gallon Fish Tank

Freshwater Aquarium Starter Kits

Before purchasing your 20 gallon fish tank, you need to decide on a few things if you haven’t already.

What kind of fish will you be keeping?

20 gallon fish tank

Tank size does matter for your fish. If you buy a baby Oscar, it will not last long in a 20 gallon fish tank and you will therefore be upgrading fairly quickly. Research the type of fish you are wanting to keep to ensure you will have adequate room for your fish in the tank that you are getting, especially if the 20 gallon fish tank you are considering purchasing is the only tank size you will be able to have.

How many fish are you planning on putting in your fish tank?

Rule of thumb is one gallon of water per inch of fish full grown.  This is where researching what fish you are planning on getting is beneficial. However, many aquarist, or new aquarist do not consider one important factor when they purchase their fish tank. Just because your tank says that it is a 20 gallon fish tank does not mean that there is in fact 20 gallons of water in the tank. Buying fish goes by how many gallons of water you actually have in the tank and not how many gallons the box says it is. If there is absolutely nothing in the tank then yes, it is a 20 gallon fish tank. But who wants a tank with no filtration, no heater, no substrate (sand, gravel, rocks), no décor and no plants?

how many fish you can put in your aquarium

Adding these things takes up space which then leaves you less than the 20 gallons. If you have a thin substrate (quarter of an inch thick) and one or two plants and a heater, you could estimate that you have lost somewhere between 1-2 gallons of water. Unless you are measuring how much water you are actually adding to the tank after everything is assembled, it is best to guess about how much water you have and then still subtract 1 or 2 gallons. Happy healthy fish is better than sick lethargic dying fish.

Are you going with fake plastic plants in your fish tank or will you have live plants?


live fish tank plants

Probably asking me if this really does matter and the answer is definitely yes it does. Why? Some plants need special lighting in order for them to grow. If you are a beginner aquarist and have never had fish before or you are still learning, personally, I would suggest going with plastic plants until you learn the ins and outs of water changes and keeping your water parameters where they need to be. Live plants can cause problems especially if they are not well taken care of.

Do you have room for a 20 gallon fish tank?

Most 20 gallon fish tanks have a dimension of 24” long, 12” wide and 16” high. This is a rough estimation of the dimensions. Make sure you have a space big enough for a tank this size and of course a flat sturdy area for the tank to sit on.

Now that we have covered the basic questions lets continue on with 20 gallon fish tanks. I have taken the liberty of going through review for these 5 fish tanks. I looked at what is included in the start up kit and read the reviews. Before we go any farther, keep this in mind. I am not sure that I have ever seen anything with a perfect review and nobody had a problem with anything in their purchase. You will have to decide for yourself if the problem they are describing will be worth the purchase or not.

Marina LED 20 gallon Fish Tank Kit

marina led aquariumKit includes:

  • Marina Slim clip on filter and cartridges
  • Natural daylight effect LED light built into the canopy
  • Fluval Max fish food
  • Aqua Plus Water Conditioner
  • Fluval Cycle Biological Supplement
  • Fish Net

This is a basic aquarium kit. Pretty good for cold water fish, but if you are going with tropical fish as many do, you will also need to purchase a heater as this aquarium kit does not come with one.

The main complaint with the reviews is the filter is noisy and the cover is flimsy. However, the filter does have a 3 piece filtration. This means that there is 3 different pieces inside of the fish tank filter that will need to be replaced. Usually not expensive to do so but is a great benefit for your tank and helping to keep it cycled. This is because, your beneficial bacteria lives in your filter.

This is what helps your aquarium thrive and helps keep your water parameters in check. Changing one pad every month will send your water parameters sideways and mess up the hard work you have done. A three part filtration will allow you to change on item a week which will help you keep your water parameters closer to where they need to be and go through possibly a mini cycle as opposed to a full out cycle. Easier to deal with and less fish deaths in your tank. If the noisy aspect does bother you, you can always purchase separately a different fish tank filter with the same setup.

This product had 4.2 stars out of 5 on Amazon with 209 reviews.

Read more reviews on Amazon about Marina LED

Aqueon Aquarium 20 Gallon Starter Kit with LED Lighting

aquaeon aquariumKit includes:

  • 100 watt heater preset to 78 degrees F
  • Quiet Filtration
  • Fish Food
  • Water Conditioner
  • Fish Net
  • Thermometer
  • Energy Saving Low Profile Hood

Pros to this fish tank is that the filter has a red LED light that will flash when it is time to change the filter or clean the filter.  This is a  great idea for those who may forget about the filter or can’t remember when the new filter was put in. Has a 5 stage filtration with an ammonia specialty filter pad.

A personal con to this is the heater. I personally am not a fan of a preset heater. There are far more benefits to getting an adjustable heater and generally are well worth the money. Ich is one benefit to getting an adjustable heater as part of the cure for ich is to raise the temperature of the water in your tank to progress the disease for faster cure. If you are breeding fish, some fish prefer slightly cooler water to breed/spawn as others may require a bit higher temperature.

Cons from Customer Reviews is that the thermometer is junk. This is more of a preference I think as to what people like. Some thermometers are easier to read for some than others. There are more accurate than others. Some people may have a few different thermometers for the same tank to make sure they are reading correctly.

Another complaint was that the lights burnt out quickly. There is no splash guard covering the lights and water splashing from air bubbles, filter, fish or from condensation burnt them out. Because the lights are built into the canopy, you must replace the entire canopy instead of just buying new bulbs. This could potentially cost tons of money in the long run and be frustrating and have you on edge.

This product has 3.9 stars out of 5 on Amazon Review with 90 reviews.

Read more reviews about Aqueon Fish Tank

Tetra 20 Gallon Aquarium Kit

tetra aquariumKit includes:

  • Scratch resistant glass tank
  • Tetra HT 20 Heater
  • Digital Thermometer
  • Aqua Safe
  • Tetra Min Fish Food
  • Fish Net
  • Tetra Whisper Filter
  • Artificial Plastic Plants

This kit includes a digital thermometer and plastic plants which is a bonus as many do not add these in their kits. There is only a few plants in this kit which helps you get started sooner if you like the plants that come standard with the kit. Pretty much the only thing this kit does not come equipped with is the substrate (gravel, rocks, sand etc..)

The biggest complaint in the reviews is the filter. It is loud and it doesn’t work properly. Personally speaking, I actually have two of these types of filters in 10 gallon fish tanks and they work just fine.  They are loud when there is not the right amount of water in the tank but that is expected with this filter and every other filter.

This product have 3.7 stars out of 5 on Amazon with 211 reviews.

Read more reviews about Tetra Aquarium

Marina Style 20 Deluxe Glass Fish Tank Kit

marina style 20Kit includes:

  • Marina Slim S20 clip on filter
  • Full spectrum canopy with 18” 15 watt Sun-Glo fluorescent bulb
  • Nutrafin Max Fish Food
  • Nutrafin AquaPlus
  • Nurtrafin Cycle
  • Fish Net
  • Thermometer

This tank does not include a heater and you would have to purchase one which could be a pro or a con. As I have said before, I personally rather an adjustable heater and most kits come with one that is preset that you cannot adjust.

The reviews for this product has me personally not wanting to purchase this online. The most complaints where about the packaging. The box was entirely too big and left much room for it to move around and having it delivered broken or completely trashed. There were a few complaints about the tank not being a 20 gallon fish tank. As I had said earlier, once you add substrate, plants, décor, filter, heater you lose space. However, I looked at the dimensions of this tank and in fact it is NOT a 20 gallon fish tank but rather an 18.7 gallon tank if filled with water completely empty.

This product has 3.7 stars out of 5 on Amazon with 27 reviews.

Read more reviews about Marina Style aquarium

SeaClear Hexagon Acrylic Aquarium Junior Executive 20 Gallon Fish Tank Kit

Kit includes:

  • 20 Gallon Acrylic Hexagon Tank
  • Full hood with 15” fluorescent fixture installed in hood
  • Power Filter
  • Plastic Plants
  • Fish Net
  • Fish Food
  • Water Conditioner

Being a Hexagon Fish Tank it will give a different look than a traditional rectangle aquarium.  However, it will also fit differently in a space than the rectangle aquarium. The hexagon shape is more of a preference in looks. The Full hood with fluorescent fixture is only that. This kit does not include the light. You will have to purchase that separately. Also does not come with a heater and if you are keeping tropical fish, this is a must. There are no reviews on this product on Amazon as to if this tank is good or bad. Because there is not light included, not entirely sure if there is filter pads included with the filter or what kind of filter it is I have included it on the end of the list.

Read more reviews about SeaClear Hexagon aquarium on Amazon

About Aquarium Kits

They are good and bad at the same time. One pro is they are cheaper than buying everything separate. One con is you spend the money on the kit then turn around a spend more money on something different than what came with the kit. Some people have never had problems with kits and enjoy them very much and still use them.

I personally have two starter kits. One is used as a hospital/quarantine tank and the other is a maternity ward for my pregnant guppies getting close to having fry. Mine did not come with a heater or plastic plants which I was fine with because I was able to add my own flare to it how I saw fit and get the perfect adjustable heater for both. The choice is always yours, read all reviews good and bad and decide for yourself. This is here to give you an idea of what you are looking at and in no way tells you which to buy for yourself.


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