» Posted by on Feb 26, 2016 in Becca N, Blog, Freshwater Fish | Comments Off on 11 Freshwater Nano Fish for Your Aquarium

11 Freshwater Nano Fish for Your Aquarium

11 Freshwater Nano Fish for Your Aquarium

Rebecca Noah


Let’s just face it: small things are cute and tiny things are even cuter. This list encompasses my favorite 11 nano species for freshwater tanks. None of the fish on the list require a tank larger than 10 gallons and majority of them can live happily in even 5 gallons.  
It is important to house tiny fish with other tiny fish. The majority of the species on this list are shy, timid, and very peaceful. They can easily be out-competed for food and stressed out if placed in aquarium with larger, more boisterous tankmates. Nearly every fish on this list could live happily together in a 10 to 20 gallon aquarium except one, the pea puffer. Pea puffers can be nasty little buggers and would be best suited in a tank all on their own.

Tiny tanks and tiny fish are adorable and very fun to set up and enjoy. It’s really cool to watch a functioning micro-ecosystem on your desk, but that does not mean that they are necessarily a good beginner tank or less work. In fact, the smaller the tank the more important regular maintenance and staying on top of water quality is. A lot of these tiny fish are also not suitable for beginners as they require special care and feedings.

Just because the tank is small and the fish are smaller doesn’t mean the workload is smaller. Always seek the advice of your friendly and knowledgeable Absolutely Fish aquarist to ensure that you are setting up your tank for success and longevity.

Stone Catfish

1: Asian Stone Catfish (Hara jerdoni)

Origin: South Asian; India

pH: 5.6-7.6

Maximum Size: 1.2”

Minimum Tank Size: 5 gallons

Diet: Likely to accept a variety of small foods including dried pellets, but should also be offered a diet of live and frozen food including bloodworms, brine shrimp, daphnia, and tubifex worms.

The Asian stone catfish is one of the cutest and smallest catfish species in the hobby. Maxing out at just over inch, this adorable, whiskered catfish makes for a unique addition to a nano tank. However, do not expect much activity from this little guy as the the stone catfish is very inactive and will likely stay in one place most of the time.

The stone catfish is very peaceful and will do well with nearly every micro species on this list. It can be housed alone, but will do better in small groups. The stone catfish would do best in an aquarium with plenty of hiding place, softer substrate, driftwood or almond leaves. Water quality is imperative to this tiny fish and must be kept stable, clean, and well oxygenated. The stone catfish is nocturnal so it’s best to feed after the tank lights go out.

Scarlet Gem

2: Scarlet Gem (Dario dario)

Origin: India


Maximum Size: .75” to 1”

Minimum Tank Size: 5 gallons for one fish, 10 gallons for a pair

Diet: Difficult to feed dried foods and should therefore be fed a variety of live and frozen food including brine shrimp, banana worms, and daphnia. Badids tend to develop diseases and become obese when fed bloodworms and tubifex worms so these should be omitted from their diet.

The scarlet badis is a stunning nano fish that has a body shape strikingly similar to that of dwarf cichlids, although there is no relation. The scarlet gem is a timid fish and very peaceful with other fish of similar size and temperament. Its best to house one male Scarlet Badis per every 5 gallons as they can be aggressive towards each other. Due to their shy and timid nature, care should be taken to ensure that they are properly fed. The scarlet badis makes for a unique addition to a small community tank. Find out more about the Scarlet Gem here!

Salt and Pepper Cory(Corydoras habrosus)

Corydoras hastatus Pygmy Cory

Corydoras habrosus

Tail Spot Cory

(Corydoras hastatus)

Pygmy Cory

(Corydoras pygmaeus)

Salt and Pepper Cory

(Corydoras habrosus)

3: Pygmy Cory Cats (Corydoras sp.)

Origin: South America

pH: 6.5-7.6

Maximum Size: 1.3”

Minimum Tank Size: 5 gallons

Diet: Omnivorous and will accept a variety of sinking foods as well as frozen food such as tubifex and bloodworms. Corydoras should never be expected to survive on the uneaten food from other tank mates and are not cleaners of an aquarium by any means.

Each of these tiny cory cats is cuter than the last and all of them originate from South America. The tail spot (C. hastatus) and pygmy cory (C. pygmaeus) will likely max out at about one inch in length, while the salt and pepper cory (C. hasbrosus) will grow to be only three-quarters of an inch long.

Pygmy corydoras are peaceful and schooling and should be kept in groups of 3-6 individuals. The different Corydora species will likely school together as well. The majority of the species in the Corydoras genus are bottom dwellers, however these mini corydoras prefer to swim in the middle levels of the water as well as the lower levels.

Sparkling Gourami
By Zikamoi – CC BY-SA 3.0
Sparkling Gourami
By Martin Fischer “Parostoteles” CC BY-SA 3.0
Sparkling Gourami

(Trichopsis pumilus)

Liquorice Gourami

(Parosphromenus deissneri)

 4: Tiny Gouramis

Origin: Asia

pH: 5.0-7.0

Maximum Size:1.5”

Minimum Tank Size: 5 gallons

Diet: Likely a micropredator in the wild and would do best on a diet of mixed live and frozen foods including daphnia, brine shrimp, bloodworms, and tubifex worms. The majority of dry foods will likely be refused initially and both gouramis will need to be trained onto dried foods.

The liquorice and sparkling gouramis are the smallest of the gouramis, each maxing out at just an inch and half. Gouramis are members of the labyrinth fishes and have a specialized organ called a labyrinth that allows them to breath air from the surface of the water. These smaller species of gouramis can be difficult to care for. They are native to slow-moving waters such as swamps, pools, and flooded fields. These habitats are rich in nutrients, low in oxygen, and very acidic. Maintaining such soft, acidic water in an aquarium can be done with the addition of driftwood, almond leaves and the use of reverse osmosis water.

The sparkling and liquorice gouramis are very peaceful and can be housed in pairs or groups and with other small, peaceful fish.

Dwarf Pea Puffer

5: Pea Puffer (Carinotetraodon travancoricus)

Origin: Southern India

pH: 7.0-7.6

Maximum Size: 1”

Minimum Tank Size: 5 gallons, preferably 10 gallons if housing 3 or more

Diet: Carnivorous, feeding primarily only small crustaceans, mollusks, and worms in the wild and will do best on a diet of frozen brine shrimp, krill, and bloodworms. Live snails should be given regularly to help keep their sharp teeth ground down, which grow continuously.

Yes, there is such a thing as freshwater puffer fish! In fact, there are several species of freshwater puffers, but this one is the smallest (and the cutest!) and can be kept in a tank as small as 5 gallons. Pea puffers max out at just over an inch in size and should only be grouped with each other, small catfish, and small gobies such as the bumble bee goby. Despite their very tiny size they can be quite aggressive and do not make suitable tankmates for other small, free-swimming fish and can be difficult to house with larger species as well. Pea puffers can also be aggressive towards each other and care should be taken to house a 1:2 ratio of males to females and no more than 3 puffers should be housed in a 5-gallon tank.

Pea puffers will do best in a tank that is heavily planted with plenty of hiding spaces and places for this curious fish to explore. Puffers are a delight to have in aquarium; they are very inquisitive and will often swim up to the glass when you approach the tank. As with all puffer fish it has the ability to inflate its stomach with water or air when threatened, puffing up to two to three times its size.

Otocinclus Catfish

6: Otocinclus Catfish (Otocinclus sp.)

Origin: South America

pH: 6.8-7.5

Maximum Size: 2”

Minimum Tank Size: 5 gallons

Diet:  Herbivorous, primarily will consume naturally growing algae in an aquarium, but will need to be supplemented as algae is eaten with algae based flakes, pellets, or wafers.

The Otocinclus catfish is one of the best and favorite algae eaters in the hobby. It does a really great job at keeping your aquarium glass, décor, and plants free of algae. The ‘Oto’ catfish is one of the smallest catfish in the Loricariidae family. These little lawn mowers have a fierce appetite and will require an algae supplement in the form of a flake or wafer if there is not enough algae present in the aquarium.

Otocinclus catfish are very peaceful and can be introduced into a number of different communities. They are a schooling fish and will do better in small groups of 2 to 6 individuals.

Bumblebee Goby

7: Bumblebee Goby (Brachygobius doriae)

Origin: Southeast Asia


Maximum Size: 1.5”

Minimum Tank Size: 5 Gallons

Diet: Carnivorous and requires a diet rich in protein and will unlikely accept anything other than frozen or live foods. Feed a variety of bloodworms, tubifex worms, daphnia, and brine shrimp.

The bumblebee goby is the only fish on this list that is actually brackish! In fact some hobbyist insist that bumblee goby does better and will be more vibrant if placed in a brackish environment. However, that is not necessarily the case as bumblebee gobies come from a variety of environments including freshwater habitats, estuaries, as well as swamps that can have very acidic waters due to high tannin levels. Therefore, the bumblebee goby is actually quite adaptive to both brackish and freshwater environments and can thrive in either.  Stable water quality and proper diet will make more of a difference to keeping this species happy and healthy than the difference in salinity will.

The bumblee goby is a relatively peaceful fish, but can be very aggressive to each other if too many are placed in a small tank. No more than one bumblebee goby should be placed in a 5 gallon tank.

Microdevario kubotai Celestichthys margaritatus
 Microdevario kubotai  Celestichthys margaritatus
 Boraras brigittae

Credit to Sonja Cygnel. Sourced from Seriously Fish
 Boraras naevus

Credit to Joseph Hoetzel. Sourced from Seriously Fish
Boraras brigittae  Boraras naevus
Espei Rasbora Sundadanio alexrodi

Credit to Joseph Hoetzel. Sourced from Seriously Fish

Rasbora espei

The largest rasbora on this list: maxing out at nearly an inch

Sundadanio axelrodi

Requires more strictly acidic conditions: pH 4.0-6.8
 Celestichthys erythromicron

Celestichthys erythromicron

8: Micro Cyprinids

Origin: Asia


Maximum Size: 0.75” to 1”

Minimum Tank Size: 5 gallons

Diet: Omnivorous and will accept a variety of small pelleted foods as well as high quality flakes and freeze dried snacks including bloodworms, daphnia, tubifex, and brine shrimp. As always it is good to feed a varied diet that includes frozen foods.

Oh, the micro rasboras! They are the tiniest of the tiny and there are so many different varieties of them. I have listed 7 of my favorites commonly stocked at Absolutely Fish.  All of these micro cyprinids are very peaceful, active, and schooling fish and would do best if stocked in groups of 5-6 or more. Many of them are also very shy and will show their best personalities if provided with plenty of hiding places and a large school to make them feel safe.


Amanda Tetra

9: Amanda Tetra (Hyphessobrycon amandae)

Origin: South America


Maximum Size: ¾ of an inch

Minimum Tank Size: 5 gallons

Diet: Will do well on a diet of small dried foods such as micro pellets and flakes. Should be supplemented with frozen brine shrimp, tubifex worms, and planktonic foods.

The Amanda Tetras, also known as Ember tetras look like tiny floating flames when placed in a school in a tank with darker substrate. Ember tetras are an active, very peaceful schooling fish and would do best in groups of 5 or more. They are native to soft water and would do best in slightly acidic waters, although they are capable of adapting to a range of hardness. Great mid-level swimming fish and will school with other small tetras such as neon tetras.

Annual Bluefin Killifish
By Cisamarc – CC BY-SA 4.0

10: Annual Bluefin Killifish (Nothobranchius rachovii)

Origin: South Africa

pH: 6.0-7.2

maximum size: 2”

Minimum Aquarium size: 5 gallons

Diet: Carnivorous surface feeder would do best on a diet of frozen brine shrimp, bloodworms, and tubifex worms.

Holy pop of color! The Nothonbranchius rochovii is an absolute stunner and makes for a great centerpiece in a nano tank. This species of killifish is a member of large group of annual killifish. Native to pools and swamps that undergo dry and wet seasons, their habitats become desiccated and complete dry out resulting in all of adult killifish to die. However, before the dry season approaches the killifish lay their eggs in the substrate and once the rainy season returns the eggs hatch and the resulting fry grow very quickly to start the life cycle over again.

In the aquarium these beautiful oddballs can be expected to live slightly longer than in the wild from 6 months to just over 1 year at most.

Endler's Livebearer

11: Endler’s Livebearers (Poecilia wingei)

Origin: Venezuela

pH: 7.0-7.6

Maximum Size: Males 1”, Females 1.5”

Minimum Tank Size: 5 gallons

Diet: Omnivorous, will accept dried food such as flakes and micropellets as well as frozen bloodworms, daphnia and brine shrimp.

Endlers livebearers are a fun, hardy, and easy species to keep and stay much smaller than their cousin the guppy (Poecilia reticulata). They are a very active fish and easy breeder for beginners. In the aquarium endlers soon learn that humans mean food, after which anytime they see a human near a tank they will go into a frenzy of begging for food. Be careful when housing endlers with guppies as they will interbreed.  Endlers are not very shy and are therefore not as fussy when it comes to hiding places and live plants. They do well in pairs as well as in small groups.

Copyright 2013 Absolutely Fish, Inc. All Rights Reserved