You probably noticed the nano aquarium is becoming more and more popular in the fishkeeping hobby! Luckily, there are many fish options available to keep in these tanks with more species being added to the nano lists all the time.
We already posted our top 10 fish recommendations for the 5 gallon Fluval Spec, as well as nano tank information, but there are some more species I think are worth mentioning.
Disclaimer: We don't recommend very small bowls or vases, in spite of their popularity. To learn why, read our Beware of Bowls blog.
All of the fish in this article do well in planted aquariums. View our list here of our Top 10 easy aquarium plants.
Sparkling is an appropriate description for this fish! Peaceful and shy, they ""sparkle"" in both appearance and ease of care in the home aquarium. As adults, they grow to about an inch and a half on average. They prefer warmer water temperatures and neutral to acidic pH levels. Plants are greatly appreciated, as well as hiding places to alleviate stress and provide more comfort. However, there needs to be some area available for open swimming as well. Sparkling gouramis are omnivores, and are not picky eaters, though their diet should varied and of high-quality ingredients for optimal health.
Least killifish are the smallest known livebearing fish in the world. They're hardy, which makes them easy to care for in many aquarium setups. Low water movement is preferred by these guys. While not terribly demanding, least killifish prefer schools in species-only tanks and do well in water temperatures between 66 and 75F. They will enjoy a heavily planted tank and utilize the plants often as a place to hide and feel more comfortable.
Colorful and small, the clown killifish will likely occupy the top of the aquarium and stay near the surface. They are known to eat mostly live and sometimes frozen foods (frozen food may need to be chopped to smaller sizes). This fish will relish fruit flies as well. Read our blog here about feeding insects and feeders to fish.
This is a unique and small fish. They are timid and get along with other small, peaceful fish, although male scarlet badis fish will sometimes fight with each other. (For the record, when I kept a school of these fish, I had no issues with fighting, but it can happen). They will thrive in a planted tank and will typically eat live or froze meaty foods. Flake foods are not always accepted by these fish. If keeping more than one male, be sure there is plenty of room for individual territories to be established.
While there are several sunfish species available, the pygmy sunfish will stay small and usually won't require a heater, although they will accept a wide temperature range, as low as 50F, and as high as 85F. They're typically more interessted in live foods, and will often take frozen foods as well, preferably daphnia, cyclops, artemia, etc. Bloodworms should only be offered on occasion - or not at all - to avoid obesity and other health issues. Baby shrimp and snails will also be hunted and consumed by this species. Many plants, driftwood, caves, rocks, etc., will help the pygmy sunfish feel secure and happy.
Dwarf golden barb
These fish are small and make a good choice for a subtropical aquarium, as their temperature range is between the mid 60s and mid 70s. Golden dwarf barbs are peaceful fish and not picky eaters - two qualities which make them ideal for many aquarists and a variey of setups. A planted tank is appreciated and will help bring out their colors. As a schooling fish, having a group of at least 6 is recommended, but the more, the merrier.
Emerald dwarf rasbora
Good water quality and consistent water parameters will make this fish easy to care for. They prefer live foods and insect larvae, and may accept frozen foods or flakes, but that will depend on the particular fish. They're compatible with other peaceful fish, and will sometimes breed in the home aquarium. Temperatures for the emerald dwarf rasbora should remain in the low 70's, up to 75F. These are shoaling fish, but feel more comfortable and are more active in a group. The males may scuffle a bit with each other. As with other fish in this list, abundant hiding spaces will be appreciated.
Rarely reaching no more than 3/4"" long, the small size, bright coloration, and peaceful nature of these fish make them a great choice for the desktop and nano aquarium. With consistent water parameters, they are easy to care for, though they are schooling fish and a group is necessary for them to thrive. The more you can add to your tank, the better. Luckily, their small size makes this easier to accomplish.
Licorice gourami are peaceful, interesting fish that will thrive in a heavily planted tank. Like some other fish listed above, they are known to eat mainly live foods, though some individuals may accept frozen foods as well. They aren't likely to eat dry food. However, they're visually striking, which makes up for the finicky eating. Fully grown, they typically reach between 1.25"" and 1.6."" Licorice gourami like soft, acidic water, with a temperature range of 72-82F.
While technically not a fish, cherry shrimp have a light bioload and can easily thrive in a small setup. They're active and extremely hardy, making them a joy to observe. Read our blog here about Keeping and Breeding Cherry Shrimp.
Two other good choices would be the dwarf crayfish or the freshwater pom pom crab, as both are small and peaceful. These are all easy to care for, though there are several things to keep in mind with inverts in general: they are good escape artists, copper is lethal to them, they will molt occasionally, and they need calcium for proper shell growth and development.
If you like small fish and/or small tanks, it is a great time to explore all the possible options available for these setups.
TFH Magazine nano tank article - https://www.tfhmagazine.com/articles/freshwater/a-big-small-change-starting-a-freshwater-nano-tank-full