In the Aquarium Hobby, It’s a Small World After All

At Aquarium Co-Op, we love fish of all sizes. How could we not? But lately, our passion has been getting smaller. Nano tanks between five and fifteen gallons, and pico tanks under five, are all the rage. For many, the realization that they could create a thriving, beautiful ecosystem right on their desk was an awakening, especially for those of us who were intimidated by the massive aquariums we admired in public institutions as kids or the pristine displays we see all over the Internet today. 

That was then.

While we always recommend working with larger tanks whenever possible, small systems enable us to enjoy nature daily without disrupting our living spaces or the people we share them with. What began as a solution to limited space has now become a passionate movement. From equipment to livestock, nearly every aspect of the hobby has been reshaped by this idea. Once upon a time, small meant a dreary goldfish bowl. Now, long and shallow “bookshelf” aquariums are growing in popularity. A petite but lively cube tank looks terrific in your kitchen next to the cookbooks. Niche hobbyists are even building fascinating ecosystems in something as small as a pickle jar.   

Undoubtedly, the concept of nano fish has expanded dramatically over the past twenty years, far surpassing the days when a local fish store only carried bread-and-butter species like neon tetras, bronze corydoras, and humble guppies. Today, many stores feature entire rows of tiny species. Particularly exciting are the new tetras being discovered in the wild as well as the stunning endler and guppy strains being created by dedicated hobbyists worldwide. At Aquarium Co-Op, we’ve leaned into our nano side, offering a thoughtful mix of unique and classic fish, along with a wide range of live plants. While we don’t sell our fish online, we can proudly point you toward trusted sources that do.

No conversation about nano tanks is complete without shrimp. After all, the word itself is often used as an adjective to describe something small. The rise of Caridina and Neocaridina species is nothing short of astounding, emblematic of the hobby’s ongoing downsizing trend. You could argue that shrimp keeping has transformed the hobby more than anything else, attracting new hobbyists and driving innovation across the board. One example of innovation is the pre-filter sponge, which not only protects shrimp from being drawn into filters but also gives them a perfect place to graze on biofilm and tiny food particles.

Feeding these miniature worlds has its own challenges. Fearful of predators, nano fish are understandably shy. And they have extremely small mouths. Getting them to come out and eat can be tricky. This inspired us to create Magic Small Fish Feed, a fine pellet designed to stay suspended in the water column rather than sinking immediately. This behavior mimics drifting microorganisms, enticing even the shyest fish to feed. Catering to nano creatures needn’t be at the expense of feeding other inhabitants. Live or frozen foods like baby brine shrimp or daphnia are readily accepted by larger community fish and bottom dwellers such as corydoras and loaches.

While Aquarium Co-Op was filming in a hobbyist’s fish room, the aquarist remarked how even her pickiest fish couldn’t resist small morsels suspended in the water column. Her normally skittish gobies darted out from their hiding spots to snatch the floating pellets. Yet her naturally more aggressive dwarf cichlids devoured the tiny food just as well. It confirmed what many fishermen already know: In the underwater world, big fish eat small food more readily than small fish eat big food.

Keeping tinier environments healthy does not mean less care is involved. On the contrary, a smaller volume of water requires we pay close attention to its quality. A dying plant or deceased fish might rapidly create a dreaded ammonia spike. Therefore, nano fish keepers must remain vigilant. This could mean more frequent water changes, especially early in the tank’s development.

Technology has a way of shrinking while improving, and thankfully, the aquarium world is no exception. There are now all kinds of stellar products designed especially for nano aquariums, including the bookshelf or cube shaped vessels. Tiny but efficient hang-on-back filters, miniature heaters, and even micro-CO2 delivery systems are readily available. Our Easy Flow Sponge Filter is a fine example. A redesigned air collar produces smaller bubbles and smoother circulation, allowing for efficient flow even in the most compact tanks. 

In many ways, the nano movement reflects one of Mother Nature’s favorite lessons: from the smallest seeds, whole forests can grow. A five-gallon shrimp tank, a betta in a well-kept setup, or a school of rasboras weaving through plants can be true showstoppers. With care and attention, these tiny worlds flourish. Proof that in the aquarium hobby, great things often come in small packages. And at Aquarium Co-Op, we’re proud to help bring them to life.