A lot has changed in the last twenty years within the marine aquarium industry.. Due to methodologies and technological advances, more people are starting and maintaining successful marine tanks that ever and the reef aquarium is an attainable goal for the average hobbyist. We can see this in the advent of the nano-reef aquarium. Once an unthinkable task, nano-reefs are now the industry staple. Twenty years ago, a successful “desktop aquarium” consisted of a 5-10 gallon glass tank with an undergravel and dolomite substrate (Moe. 308). I look around our office, and think to myself that things have changed indeed!

Simple 10 gallon tank set ups with air pumps and incandescent bulbs have been replaced by tuned up nano-reefs. Tanks in our office are outfitted with protein skimmers, additional flow, deep sand beds, and power compact lighting. One of my coworkers even uses an Aqua Controller Jr.!

There are more products in the market now, than ever, to cater to the small tank enthusiast. All-in-one set ups are made, fine tuned, and shipped out in droves. Nano-reefs are the hottest trend in the industry, but as with all trends, we need to step back and look at what we are doing. As said before, while building the reef aquarium is an engaging and fulfilling thing to do, we must remember that we have a responsibility to the animals that we keep. We must work hard to provide an environment in which they can thrive.

What is a Nano Reef?

When looking at the ocean and its huge expanses of coral reefs, in comparison, any in-home representation can be considered a mini-reef. In practice, midsize mini-reefs ranging from 40-100 gallons have become common place. They fit easily into the average home, allow for most commonly available animals to be kept, and are reasonably affordable. Nano-reefs are even smaller representations of the reef. They range from 1-30 gallons. They fit easily onto a work desk or countertop.

Considerations for the Small Tank Enthusiast

Although nano-reefs are less expensive than a larger tank to set up, they are not, by any means, easier. Imagine that you have a five gallon tank and a five hundred gallon tank in the same room. Now place a dead or dying anemone into each. Which tank would crash first? If you said the five gallon tank, you are correct.

Smaller tanks simply lack the stability and buffering capacity of larger tanks. As the above example depicts, they can be finicky, difficult to stabilize, and in the case of a mishap, can crash within hours. Everything from temperature, to salinity can swing in a heartbeat.

When considering a nano-reef, do the research behind normal reef husbandry, and take a few extra precautions. Always be prepared to do a large water change in case of an emergency. Keep some fresh saltwater prepared and keep a close eye on the inhabitants. Remember, nano-reefs are a challenge!

Stocking the Nano Reef Aquarium

There are many more obstacles in keeping a smaller tank than a midsized or larger one. In addition to stability, great care should be taken when choosing the animals that you wish to keep. “The key to keeping marine organisms in a mini tank is to be lean and selective” (Moe, 311). Although you may see many densely stocked nano-reefs online or at high quality local fish stores, keep in mind that there was foresight and planning behind the tank.

Before you purchase any animal, take the time and plan out what you want to keep. Online vendors, such as ourselves, catalog the many plants and animals available, and provide brief descriptions of compatibility, diet, and distribution. When planning your nano tank, browse through our selection here, and bookmark especially interesting animals. When planning the nano reef, there are three especially important considerations you must make before purchasing each animal.

Size and Distribution

The first rule in stocking any aquarium is to buy animals that as adults will fare well in your tank. Many animals are absolutely precious as juveniles, but become monsters as they age. For instance, the panther grouper is a charming animal when small. Their fins and coloration make them attractive, while their personality and intelligence make them personable. They fare well in small tanks when less than 4 inches, but can quickly grow to over a foot long.

Also keep in mind the natural distribution of the animal that you are keeping. Clownfish are particularly well suited for aquarium life because they never occupy a space in nature more than two square feet. Mandarin Dragonets, though roughly equal in size, occupy much larger tracts of land to hunt and feed. As such, they are suited for only mid sized to larger tanks.


Although many smaller animals are perfectly suitable for smaller tanks, be prepared to have them as the sole occupants. For instance, dottybacks, damsels, and larger clownfish such as the clarki, or tomato clown, are all great candidates for the nano reef aquarium. However, many will not tolerate other animals in their space.

Territoriality is not limited to fish. Many corals also exhibit strong territoriality. Galaxea, frogspawn and hydnopora are all corals that are extremely aggressive, and can harm corals within their general vicinity. These animals have long sweeper tentacles that help it secure its space from other encroaching corals. Galaxea in particular, can harm and kill corals within a foot of it.

Soft corals can also exhibit quite a bit of territoriality in the form of chemical warfare. Palythoa, and zooanthids have the capacity to release low levels of toxins into the tank, to inhibit the growth of competitors. In polyp-dominated tanks, this is rarely a problem. However, dense populations can prevent one from creating a mixed reef with small polyp stony corals.

Bio Load

One of the most common questions in the reef hobby is “how many fish can I have in a ____ gallon tank?” Many people try to boil it down to a simple “inch per gallon” rule. However, it is rarely that simple. Some small animals, though small, require large quantities of food. Some animals, require large tracts of space, and other animals prefer to be in large social groups.

A good example would be the anthias. Anthias are relatively small, hardy animals that fare well in aquaria. As planktivores on the reef wall, they constantly feed, and have extremely high metabolisms. They also live in large social groups, with schools that cover acres of the reef wall. Though they may fit in the traditional “inch per gallon” sense, they are anything but suitable for the nano-reef.

So How do I Stock my Nano Tank?

This is anything but a simple answer. Some animals are not appropriate for the nano reef, while others great, but limit your choices for other organisms. Take your time, do the research and plan ahead. My best suggestion would be to shop around!

Interesting Candidates for the Nano Reef Aquarium

If ever there were an arena for a species or region specific tank, the nano- reef would be it. They allow you to explore and accentuate the eccentricities of the reef world on such a small scale. Relationships that would otherwise go unnoticed are in full view in the Nano reef.


The family gobiidae is one of the most diverse animal group. There are almost 2000 named species, and many more to be named (Debelius, 1040). Small and peculiar, many gobies are particularly suited for aquarium life.

The Neon Goby is a personal favorite. Often ignored in the larger reef setting, the nano tank showcases their playful personality. Purchased in small groups or pairs, it is not uncommon to have them breed in captivity. They serve as natural cleanerfish for other larger fish, but do not need to do so to survive. Another Marine Depot staff member has a pair that shares a barnacle hole as a home, and come out to play and feed.

Prawn gobies are particularly interesting in small tanks, and allow us to see one of the most unusual social interactions in the reef. The pistol shrimp and prawn goby often form a symbiotic pair. The blind pistol shrimp and prawn goby share a burrow. While the pistol shrimp builds the home, the prawn goby often stands guard. There are many attractive pairs, such as the yasha hashe goby and randall’s pistol shrimp, that are easily obtained and showcased in a nano reef.

Aggressive and Interesting Reef Oddities

There are many animals that you would dread putting into your display tank, that are easily showcased and appreciated in the nano reef. Many animals are simply too aggressive in the main tank, or are not easily maintained. Here are a few exceptional animals to consider as the focus for your nano reef.

Aggressive fish, such as the angler, scorpionfish, or fumanchu lion, are often overlooked as reef-safe fish. In larger tanks, there are often too many other prized fish to risk purchasing such beauties. In the nano tank, they become the center of the tank. Anglers, scorpionfish, and lions are spectacular animals that warrant attention, and have very peculiar personalities. Another Marine Depot Staff member kept a small angler in his tank named Joseph. He was a favorite among the accounting girls for his meek personality, and ferocious appetite. Keep in mind that these animals are dangerous, and should be handled carefully.

Another nano-reef favorite is the mantis shrimp. Stomatopods can easily be the most beautiful or spectacular crustacean. They are ferocious, and have earned the name “thumb splitters” for good reason. Often these animals come in as pests in the liverock, skulking around the tank, and taking prized fish as their victims. Rarely seen, in large tanks, they can wreak havoc. In a nano-reef, however, they can thrive. Their unique personalities and eccentricities are revealed. Occasionally, beautifully colored peacock mantis shrimp come in and wow customers.

The last animal is a true favorite of mine—the harlequin shrimp. These are the smallest marvel of the aquarium, and require expert care. Hobbyists are often mesmerized by its coloration and shape. However, they have an extremely specialized diet, and can only eat the suction feet of starfish. In larger tanks, they often perish trying to find food. In nano-reefs, however, you can easily feed them with a steady diet of chocolate chip starfish. Keep in mind that you must still discard of the carcass quickly, and feed them regularly.