Home Improvement

Everything to Know About a 25-Gallon Fish Tank

Fish are the third most popular pet, in large part because their aquariums create beautiful landscapes that you can admire in your home. Though they are less interactive than cats and dogs, they can still provide both education and entertainment.

However, there’s a common misconception that fish are easy or inexpensive to own. While they don’t need play time or frequent vet visits, they do need an environment that supports their health and well-being.

Today, we’re here to talk about the 25-gallon fish tank. How many fish can this tank hold? How can you make sure that you’re keeping up with aquarium maintenance with a tank this size?

Read on to learn everything you need to know about 25-gallon fish tanks.

Can’t I Just Buy a Fish Bowl?

When you envision your future fish’s home, you might be imagining them swimming around in the classic fish bowl. The reality is that fish bowls aren’t good for any fish, even tiny ones.

For starters, fish bowls are not stable environments. Fish bowls don’t contain filters and don’t contain very much water. As a result, it’s almost impossible to achieve a stable chemical balance that promotes fish health and environmental cleanliness.

The shape of the classic fish bowl also presents some concerns. The curved glass distorts your fish’s vision, causing confusion and distress. Between this mental confusion and the confinement of a fish bowl, your fish may swim into the glass often, which can cause injuries and even more anxiety.

How Many Fish Can a 25-Gallon Fish Tank Hold?

In the aquarium enthusiast community, the general rule of thumb is that you can have one inch of fish for every one to two gallons of water. In other words, if your fish are about one inch in length, you can have somewhere between 12 and 25 fish before things get overcrowded. However, this rule doesn’t always apply well to all breeds, so make sure that you do breed-specific research before introducing fish to their new home.

Keep in mind that in the right environment, fish will start to breed, which will drastically increase the population in your aquarium. If you’re going to put male and female fish of the same species together in a tank, be prepared to purchase another tank to relocate some of the offspring as they grow. If you’re aiming to grow your fish population, keep in mind that female fish may eat their offspring.

What Kind of Fish Thrive in a 25-Gallon Aquarium?

When you shop for aquariums, you should have a sense of what kinds of fish (and other aquatic critters) you want to take care of. 25 gallons may sound like a lot, but it isn’t enough space for larger breeds like angelfish, suckerfish, or silver dollars, which are better suited to 50-gallon tanks or larger.

The key is to focus on breeds that won’t grow much more than an inch in length. This includes breeds like:

  • Swordtails
  • Platys
  • Mollies
  • Corydoras
  • Dwarf gourami
  • Tetras
  • Guppies
  • Harlequin Rasbora

You can also introduce other species like certain kinds of shrimp and snails. If you intend to create a mixed community of fish or fish and other species, make sure that they can coexist peacefully without disrupting one another’s environments. Certain breeds are known for their aggression and may wreak havoc on your aquatic community.

What Equipment Will I Need?

As we mentioned earlier, fish can become relatively low maintenance with time. However, you need to prepare for high upfront costs if you want to create a healthy and happy environment for your pets. In addition to the tank itself, you’re going to need to invest in the following equipment.

Filters and Skimmers

Unless you’re purchasing an all-in-one tank, you’ll need to purchase what is often called a hang-on-back filter. The filter you choose needs to be graded for a 25-gallon tank or higher (and you will need to manually lower the filter flow if your filter falls in the latter category). Filters help to keep your water moving, clean, and clear.

If you plan to have several fish in your 25-gallon tank, you may not want to do 20% water changes on a regular basis. This is where protein skimmers come in handy, as they can keep algae growth under control.

Water Additives and Test Kits

Tap water does not have the right salinity or pH balance for most fish, which means that you’ll need the right chemical additives and test kits to keep this balance in check. Different types of tanks (think salt vs. freshwater) require different additives, so always make sure that you’re purchasing habitat-specific products. Follow instructions carefully to avoid shocking your fish when you do partial or full water changes.


Light provides both oxygen and energy for your fish, the healthy bacteria growth in the tank, and any natural plants or coral you may incorporate into your tank. Some tanks come with lights built into the lid, which can make your setup much easier. However, you may need to replace the bulb with one suited to your habitat (ie a full-spectrum reef bulb for certain coral systems).

Sediment and Decorations

Finally, you need to provide your fish with places to rest, hide, and play! Start with a bed of live rocks that will provide plenty of nooks and crannies for bacteria growth and security for your littlest fish. Then, add in colorful decorations in a variety of sizes, including fake logs and plants (or, alternatively, real plants, which require more upfront maintenance but can contribute to a balanced system in the long run).

Create the Perfect Home for Your Pet Fish

Having a 25-gallon fish tank in your home can provide more joy than you may think. The liveliness and color it brings to any room will keep you entertained without overburdening you with constant pet care. Use this guide to ensure that your 25-gallon fish tank is suitable for your pet fish.

Looking for more helpful guides? Take a look around as we cover everything from health to business and beyond on our blog.

Fazal Abbas

My name is Fazal Abbas, and I am a highly skilled and accomplished blogger with a passion for creating engaging and informative content. Over the years, I have honed my writing skills and developed a deep understanding of what resonates with readers. As a blogger, I am confident that I can deliver the high-quality content that my clients and readers expect, and I am committed to staying up-to-date with the latest trends and developments in the industry. I am always looking for new ways to innovate and push the boundaries of what is possible in the world of blogging and content creation.

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