10 Best Fish for a 15-Gallon Tank
Posted by on 4/25/2025
Hobbyists looking for a tank that’s not too large, but big enough to house some of the more popular fish in the hobby may find the 15-gallon aquarium the perfect size. In this post, we’re going to recommend 10 stocking options for a tank of this size.
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Celestial Pearl Danios
Native to Myanmar, Celestial Pearl Danios top our list, and we've featured them on some of the other best-of lists, such as 10 Best Nano Fish for a Shrimp Tank, and 20 Best Fish for a 10 Gallon Aquarium. They are excellent, peaceful schooling fish, but there is one important piece of information hobbyists should know. From viewing far away, these fish will appear mostly brown. Only when the hobbyist views the fish close to the tank, will they see their "galactic color pattern" which hobbyists adore.
Betta Fish
The Betta Fish is an aquarium staple for a reason. We've seen the fish featured in Hollywood movies such as James Bond's From Russia With Love, and it's for good reason. They're gorgeous and easy to care for freshwater fish. The species is often recommended for aquarium beginners. However, their care requirements are some of the most misunderstood. Betta Fish do best when kept alone, without tank mates in most cases. A gorgeous betta will make for an excellent centerpiece fish in a 15-gallon tank.
Green Neon Tetra
At first glance, hobbyists may notice that these fish don't necessarily look neon green. In reality, they display a more blue coloration but do have a slight green shimmer. These fish tend to be a bit smaller than the traditional neon tetra, and they are also known to "color up" meaning - they'll only display their brightest coloration once the aquarium lights turn on.
Cardinal Tetras
One of the most popular aquarium fish in the hobby - the cardinal tetra is an aquarium staple. These fish, native to South America, are known for their hardiness and vibrant red stripes that cover the lower portion of their bodies. Cardinal Tetras are peaceful fish and make for a great schooling fish option for hobbyists owning a 15 gallon aquarium.
Ember Tetras
Named after their ember-like appearance, Ember Tetras might be the smallest fish mentioned on this list. These fish, growing to reach .8 inches in length, are quite tiny. Similar to other tetras, these fish are incredibly easy to care for. They're perfect for a planted aquarium, where there orange coloration contrast nicely with a green, plant filled backdrop.
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Blue Moscow Guppies
Moscow guppies are a linebred color morph of the traditional guppy (Poecilia reticulata). With breeding origins originating in Russia, there are quite a few "Moscow" guppy color variations. These guppies display one true color, with some color variations being a bit more rare than others. While Blue Moscows are slightly more common, they're equally as beautiful compared to the rarer purple moscow color variant.
Endlers
Similar to the guppy, endlers are live-bearing fish, meaning they have a high propensity to breed. Hobbyists should strongly consider this before purchasing Endlers, as they can quickly take over an aquarium. Because of this, many Light Fish sellers, will only sell exclusively males or females. However, hobbyists wanting to breed these fish may want to consider a male-female pair. Just like the guppy fish, there are plenty of unique strains and color variations to choose from, with a wide variety of price ranges to match.
Dwarf Cichlids
The term dwarf cichlid encompasses a variety of different species, ram cichlids, and apistogramma cactuioides are just a few of many dwarf cichlids seen in the hobby. In a 15-gallon setup, these fish can function as a single species centerpiece fish, or a duo. Just be sure to do your research regarding gender and temperament on whatever species you choose, as certain fish can be a bit more aggressive than others.
Pineapple Swordtail Mollies
Next on our list is the pineapple swordtail molly. This fish is different than the traditional molly, in that it has a "sword-like" tail and pineapple coloration. These fish are easy to care for, small in size, and make a great schooling fish for a 15-gallon tank. Their sword-like tails are the result of crossbreeding, and will catch the attention of those fortunate enough to gaze upon your tank!
Metal Black Snake Skin Guppies
Last on our list is a unique guppy color variant, the Metal Black Snake Skin Guppy. These fish feature a black coloration, with an iridescent shimmer, a result of linebreeding different color variations of the traditional guppy fish. While often hard to find for sale, these fish share the same care requirements as a traditional guppy, but provide a unique color not often found in freshwater aquarium-safe fish.
Conclusion
That wraps up our list of the best fish for a 15-gallon tank. As you can see, there is no shortage of options to choose from, and your decision will likely come down to whether or not you prefer a schooling fish, or a centerpiece fish to stock your tank. No matter which route you go, you'll be sure to love all that these species have to offer!
If you're looking to acquire some of these fish, be sure to visit our marketplace, where you can shop directly from experienced hobbyists!
Miles Harrison
With over a decade of aquarium experience, Miles can be found writing about saltwater and freshwater aquariums. When he’s not writing about fish, you can find him going for a run or building websites, such as this one!
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