11 Blue Freshwater Fish for Your Aquarium

Freshwater fish come in all sorts of shapes, sizes, and colors. From red to green, blue to yellow, there is an assortment available for every person’s style. This list contains blue freshwater fish that can be kept in an aquarium. This list does not cover all of the blue colored freshwater fish. There are many more out there, but I wanted to showcase many that are either very popular or stand out to me. As a disclaimer before we continue, not every fish on this list is compatible with one another.

1. Neon Tetra

The first on our list is the Neon Tetra (Paracheirodon innesi). These small schooling freshwater fish are vibrant blue and red and do best in groups of 6 or more. They only grow to be about 1.25″ so remain incredibly small. They’re incredibly peaceful fish and should not pick on other fish, and they look amazing weaving in-between plants in an aquarium. They’re an excellent choice for an aquarium if you’re looking for a small pop of color.

2. Neon Dwarf Rainbowfish

Praecox Rainbows (Melanotaenia praecox), sometimes called Neon Dwarf Rainbow or Dwarf Neon Rainbow are a species of schooling fish that grow to about 3″. This blue tropical fish is incredibly peaceful and will do best in 20 gallons or larger aquariums. I would highly recommend keeping them in schools of 6 or larger. They will do best in well-planted aquariums with some open swimming areas.

3. Guppies

Guppies come in all sorts of colors. You’ll often see them in orange, yellow, silver, or red varieties. There are plenty of guppies that come in different shades of blue, some are the Blue Moscow Guppy, Blue Koi Guppy, Blue Dragon Guppy, and many others. If you’re not looking for specific guppy strains, you should still be able to find nice blue colored ones at your local fish store.

Overall, guppies should be fairly easy to care for, they’re great for community tanks and do well in 10-gallon fish tanks or larger. They likely won’t bother other fish, but males may be aggressive toward one another. I would recommend keeping all males together (minimum of 6) or keeping a ratio of 1 male to 3 females. The males may chase the females around so it’s important to have more females to not stress out a single one. Keep in mind this fish species breeds very quickly, and produces live offspring so if you mix males and females you’re bound to get an overpopulation of guppies.

4. Bettafish

Just like guppies, bettafish also come in an assortment of colors, blue being one of them. A minimum of 10 gallons is recommended for a male betta, and there should only be one male betta in a freshwater aquarium because they will fight others of the same species to death. Females may co-exist in a sorority-type setup, but they’re also not as “flashy” as males. Males & Female Bettas should do fine with other community fish. Check out the Betta Complete Care Guide to learn more about them.

5. Cardinal Tetra

The Cardinal Tetra (Paracheirodon axelrodi) is another blue freshwater aquarium fish. This fish species looks similar to the Neon Tetra but has bolder blues and reds on its body. They’re vibrant fish that grow to about 2″ in size. Cardinal Tetras love heavily planted aquariums with slow-moving waters. They’re much harder to keep successfully due to their sensitivity to water parameter fluctuations. They grow to about 2″ as adults and do best in aquariums that are 10 gallons or larger. If you’re a veteran fish keeper, I would consider checking out this fish species!

6. Demasoni Cichlid

The males of the Demasoni Cichlid have vibrant blue and black stripes running vertically throughout their bodies. Native to Lake Malawi in Africa, this species of fish requires higher KH & pH levels to keep them happy. Due to their aggressive personalities, Demasoni Cichlids should be kept with other Mbuna Cichlids in at least 55-gallon fish tanks. Mbunas are usually overpopulated to help deter aggression, which is counterintuitive to how you normally keep fish. Overpopulating an aquarium will require more filtration due to the increase in bio-load and waste.

7. Discus

Discus are slightly more niche fish that come in the blue variety. The Blue Diamond, Royal Blue, and Cobalt Blue Discus are a few that come to mind. Discus does best in waters that are in the low to mid-80s (°F). If you are on the hunt for a heater, take a look at the 6 Best Heaters for Freshwater and Saltwater Aquariums. Water quality (low nitrates and phosphates) is also incredibly important to successfully keep Discus. Some beginners to Discus opt into keeping them in bare-bottom fish tanks to prevent the buildup of uneaten food and fish waste.

These fish can grow between 6 and 8 inches and do better in taller aquariums. I would personally avoid keeping groups of Discus in aquariums smaller than 75 gallons. Be sure to do thorough research on this fish before committing to keeping them! Their colors compete with many saltwater fish, and it’s very rewarding to keep them successfully.

8. Gourami

There are many different types of Gouramis. Colors range from red, silver, white, blue, and more. Common types of Blue Gouramis include the Neon Blue Dwarf Gourami, Blue Gourami, Powder Blue Dwarf Gourami, and Blue Paradise. These are all different types of Gouramis that will range in size, water parameter requirements, and temperaments. Unfortunately, this article will not deep dive into the requirements of each, but information can be easily found.

9. German Blue Ram

The German Blue Ram (Mikrogeophagus ramirezi) is a beautiful South American Cichlid that has vibrant blue dots speckled throughout its body. They grow to a little under 3″ in length and are often kept as a male/female pair. Like most cichlids, this species becomes incredibly territorial when laying eggs. Otherwise, they usually keep to themselves. They do well in planted aquariums no smaller than 30 gallons with plenty of nooks and hiding spots.

10. Electric Blue Acara

Electric Blue Acaras (Andinoacara pulcher) are large blue freshwater fish from South America. They grow to about 5″ when fully sized and have remarkable colorations. They do best in 55-gallon fish tanks or larger. They will do well in aquariums with similar-sized fish. Smaller fish may become a snack for the Blue Acara. They usually mind their own but will likely become very territorial when breeding. Both males and females work together to protect eggs after they are laid.

11. Electric Blue Jack Dempsey

The Electric Blue Jack Dempsey is probably one of the most vibrant blue colored freshwater fish I have seen. This large blue tropical fish grows to about 10″, and is easy to care for but is very aggressive. They will likely eat any fish smaller than them and will hold their own against many other aggressive cichlids. A single Jack Dempsey will do fine in a 55-gallon fish tank, but if you want to add any more fish, you’ll likely need an aquarium that is much larger (100+ gallons) once they grow.

Final Notes

Deciding what fish to keep in an aquarium is one of the hardest choices in this hobby. This list hopefully will steer anyone in the right direction to find the perfect blue colored fish! As stated before, this list does not cover every species available, but it gives a good idea on the variety out there. If you’re on a deep dive for all things freshwater, check out some really cool Bottom Feeders for Freshwater Aquariums.