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Keeping mini-aquariums, also referred to as nano-aquariums, is of burgeoning interest to many aquarists. Although there is not yet a consensus as to the exact definition of a mini-aquarium, it typically refers to tanks that are less than 15 gallons (60 l) in total volume. These relatively small setups can house freshwater or marine species. Many are self-contained units that include lighting and filtration systems integrated as part of the aquarium itself.
I Had One of Those When I Was Ten!
Many of us had a goldfish in a bowl as a first pet—was this some kind of early “mini-aquarium”? In a word, no. Mini-aquariums are meant to showcase the concept of an aquarium at a micro level. They feature miniaturized equipment, such as reef-caliber nano lights, nano power filters, tiny heaters, and miniature skimmers. And these aquariums in miniature take a lot of skill to keep. A simple goldfish bowl (which, by the way, is terrible for goldfish, as they do not thrive in such a small space) just can’t compare to the complexity of a well-kept mini-aquarium.
Mini-Aquarium Pros
Mini-aquariums can be wondrous to behold. They have many advantages over larger tanks, including:
  • The size makes them perfect for desktops and small areas.
  • The tanks’ smaller size and reduced weight make them acceptable in small living spaces, like apartments, that may not allow very heavy tanks.
  • The reduced size allows more freedom when it comes to the shape of the tank itself; there are many interesting forms of mini-aquaria, including round, hexagonal, bow-front, and other nontraditional tank shapes.
  • You can focus on species that would get lost in larger tanks.
  • Shy species are more visible in a mini-aquarium.
  • A single specimen of a species that can’t be displayed with other fish can be displayed in a mini-aquarium.
Mini-Aquarium Cons
There are also some disadvantages to these small setups, including:
  • They are more difficult to keep than larger tanks, because stable water chemistry and thermal stability are harder to maintain in a small tank; they are not for beginners.
  • Proper cycling is even more important in a smaller tank because the margin of error is reduced.
  • Desktop tanks have more safety issues, including lessened stability (they are more likely to be knocked over) and electrical problems (cords are more likely to be out in the open).
Choosing Fish for Your Mini-Aquarium
Many freshwater and marine species can do well in a mini-aquarium. Tips on picking the right fish for your tank include:
  • Select species that grow to no more than 2 inches (5 cm).
  • Choose species that are not overly active.
  • Don’t stock fish known to prey on each other.
  • Don’t stock timid species with aggressive ones.
  • Don’t house species that share the same dwelling or feeding habits—you’ll just create competition, which leads to aggression.
Freshwater Species
Suitable freshwater species for a mini-aquarium may include:
  • Small rasboras (such as Boraras brigittae, Microrasbora erythromicron, Rasbora brittani): tiny schooling fish; peaceful; can be in danger from larger tankmates
  • Barbs (such as Barbus jae, Barboides gracilis): schooling fish; chunky bodies; outgoing personalities
  • American tetras (such as Hemigrammus bellottii, Paracheirodon innesi): schooling fish that move slowly as a unit
Marine Species
Suitable marine species for a mini-aquarium may include:
  • Neon gobies (such as Elacatinus oceanops, E. randalli): thin, tapered bodies; peaceful; tank cleaners
  • Clownfish (such as Amphiprion percula, A. ocellaris): small; peaceful
  • Dwarf angelfish (such as Centropyge argi, C. fisheri): large variety of colors and patterns; can be tamed; assertive but will settle down with noncompetitive tankmates
Mini-aquariums provide a fascinating glimpse of the beauty of an aquarium in miniature. Although they aren’t for beginners, the proliferation of new nano-equipment and the continuing introduction of smaller species into the hobby means that mini-aquariums are safer and easier to keep than ever before.