5 Best Small Fish for Fluval Edge Tank (6-Gallon)

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Nano tanks have gained increased popularity over the past several years, and for good reasons. Although they are slightly more demanding in terms of cleaning and maintenance, they are also extremely rewarding visually speaking. Nothing beats the style of a Fluval edge tank with a handful of vibrant and colorful occupants bringing it to life.

Today, we will discuss crafting and stabilizing a nano environment in a Fluval edge setting. More precisely, we will talk about the fish you can use for your Fluval edge 6-gallon tank.

Small Fish for Fluval Edge Tank

So, here are the 5 best fish species you can keep in a Fluval Edge 6-gallon fish tank:

– Betta


Bettas are some of the most splendid aquarium fish, thanks to their large fins and astounding color and pattern diversity. These fish can grow up to 2.5-3 inches, so they remain fairly small but appear larger due to their veiled tails.

Bettas are adaptable and hardy fish that can withstand a variety of environmental conditions. The ideal temperature should remain around 75-85 °F with a pH of 6.8 to 7.5. This fish is easy to maintain long-term since it isn’t too pretentious about its diet or environmental conditions. So long as your betta has a protein-rich diet and a clean habitat, it will thrive.

Special Mentions

Do not house more than 1 betta in your Fluval edge tank. Theoretically, you could have 2-3 bettas in a 6-gallon setting, but I don’t recommend it. These fish aren’t exactly social, so they will get into fighting when overcrowded. Males are also incompatible with each other, no matter the tank’s size.

Also, keep in mind that bettas are labyrinth fish. So, allow them the space to reach the water’s surface for their occasional gulps of air. And don’t crowd their habitat with too many plants and decorations. These fish have large fins and can get hurt easily in an overcrowded setting.

– Guppies


Guppies don’t need any introduction. These are adaptable and resilient fish, capable of thriving in both nano and full-sized tanks. Guppies grow up to 2-2.5 inches (in the case of females) but usually remain below 2. This allows you up to 3 guppies, provided that one fish requires 2 gallons of water to remain comfortable and happy in its habitat.

Guppies are omnivorous, so they’re easy to feed and are very easy to maintain, making them the ideal choice for a beginner aquarist. They are also amazingly diverse in terms of color, pattern, and fin and tail shapes, providing you with a large pool of options.

Special Mentions

Guppies are some of the most prolific breeders in the aquarium world. The guppy female can produce offspring monthly for 12-16 months at least, sometimes even without a male present. This means you should be very careful where you’re sourcing your guppies.

The reason is that guppy females store the male’s sperm up to 10-12 months inside a special abdominal pouch. They can then use the sperm to self-impregnate every month and produce offspring even in the absence of any male. You obviously don’t want that because you only have 6 gallons at your disposal, which is enough for 3 adult guppies-only.

If you don’t want your guppies to breed, get 3 females and make sure they haven’t had contact with any male for at least several months. Or get them while they’re still sexually undeveloped to eliminate the risk of surprise pregnancy altogether.

– Endler Guppies


Endler guppies are slightly different than normal guppies. The main differences between them include:

  • Endlers are smaller than guppies, only growing up to 1.8 inches in the case of females, while males remain below 1 inch
  • Endlers are slim-bodied, compared to the guppies’ stockier appearance
  • Endlers lack the large fins and tails that have made guppies so popular in the aquarium world

Other differences include color and body patterns, but everything else is pretty much the same. They have the same diets, same social behavior, and are both live bearers, capable of delivering young monthly.

Because Endler guppies are smaller, you can have 4-5 specimens in your 6-gallon Fluval edge setting.

Special Mentions

Avoid males. You should create a female-only Endler society to prevent breeding, given that your 6-gallon setup won’t allow your guppies to multiply. Also, keep in mind that guppies and Endlers can interbreed to create hybrids, which are not as viable as purebred fish.

So, don’t mix male guppies with female Endlers and vice-versa.

– Ember Tetras

Few fish are as iconic as ember tetras. These tiny swimmers are destined to populate nano environments thanks to their joyful and peaceful presence and small profile. Ember tetras rarely, if ever, get to 1 inch in size and like to live in larger schools to feel safe and comfortable in their habitat.

The standard recommended tank size is 10 gallons for a school of 8-10 fish, but you can have 5-6 of them in your 6-gallon setting. Provide tetras with temperatures around 70-82 F and keep their water clean and well oxygenated, and they will thrive.

Special Mentions

While ember tetras are fairly easy to keep, these fish are more sensitive than other species. They cannot withstand aggressive changes in water parameters and need a cleaner environment to remain healthy and calm. Poor water conditions will cause tetras to experience stress and fall sick as a result.

When it comes to creating a stable tetra society, remember that these fish are easy to breed. Avoid males altogether or have a nursing tank ready for when females get gravid and need to deliver. You can do with the fry what you please, including setting up a new tank, gifting them to friends, or even selling them online. Don’t expect any record-breaking payday because tetras are cheap. On average, you can get a school of 5 for $2-5.

– Sparkling Gourami

Few fish beat the sparkling gourami in terms of presence and style. Not only is the fish unique in appearance (brown body with dark-brown spots and spotted white fins), but in behavior also. Sparkling gouramis are known as talking fish because they use a subtle crackling sound to communicate with each other. Listening to your nano fish ‘speak’ to each other will make for quite the eerie experience, as you might suspect.

These fish only grow up to 1.5 inches but require more space than fish of their size would. So, you can only keep between 1 and 3 sparkling gourami in your 6-gallon nano tank.

Special Mentions

This shoaling species feels more comfortable in groups of 5-7 individuals. So, try to house at least a pair or 3 fish, provided that the setting allows it.

Also, this is a labyrinth fish, just like bettas. Provide them with easy access to the water’s surface to allow them to breathe easily. Their labyrinth allows them to withstand poorer water conditions than other fish, which is why they’re ideal for novice aquarists who tend to make more mistakes along the way.

Tips on Maintaining Your Fluval Edge Tank

  • Monitor water parameters – This is an essential point when it comes to maintaining nano tanks. In general, smaller tanks require more maintenance and cleaning than larger ones. The reason is that ammonia and nitrates accumulate faster in a smaller environment. Get yourself a water tester kit and evaluate the water chemistry and parameters at least once every 2-3 days.
  • Vacuum the substrate – Go for gravel, as this type of substrate is easier to vacuum and keep clean. You should vacuum the substrate regularly, 2-3 times per week, to keep the fish’s habitat clean and healthy.
  • Partial water changes – At least 2 15-20% partial water changes per week are necessary to keep the habitat well-oxygenated and clean. The frequency of your water changes also depends on the fish you’re housing and how messy they are.
  • Regular cleaning – You should ideally remove fish waste and food residues as often as you can. Also, have an algae deterrent in place, whether it’s manual cleaning, live plants, or even algae eaters like plecos, should the tank’s layout allow it.

In essence, cleaning and maintaining a nano tank isn’t much different than maintaining a larger aquarium. The only difference is in the frequency of the cleaning.


Fluval edge tanks can become amazing pieces of art in the right hands. The aquascape makes a huge difference in this sense, but so do the tank’s inhabitants. Consider today’s list of small fish and choose the one(s) that appeal to you the most.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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