Stocking A Reef Tank – Not As Easy As You Thought

It’s hard not to be captivated and inspired by a large, established reef system with lots of colorful fish and growing corals that gently sway under the shimmer of bright lighting. We immediately imagine having one of our own, instantly full of fast growing acropora and mandarin gobies! However, what we don’t see is that the established reef system in front of us is the result of years of research, water testing and diligent husbandry. We don’t see the progression from the easier to keep corals in his (or her) first tank that led to the purchase of that first acropora frag, that eventually grew into the brightly colored, thick branched colony before us. We imagine quick success and easily obtainable results. The purpose of this article is to help you to avoid making mistakes when it comes to stocking your reef system so that you can enjoy a successful reef tank and avoid losses from trial and error.

Know Your Limits

It doesn’t matter whether your first tank is 4 gallons or 400 gallons. There are going to be some limitations on what fish and corals you can keep in each system. Especially during the first few months or perhaps longer, each system is a little different. For example, acropora and SPS corals require stable water chemistry and low phosphate levels. Until you can manage your tank’s water chemistry to maintain stability, it is unlikely that SPS corals will survive in it due to natural fluctuations that occur in every system. Managing these fluctuations requires a lot of input from the reef keeper, regular water testing, dosing, water changes and so on. It’s important to note that there are lots of ways to keep a successful reef tank and there some exceptions to these general rules.  In most cases however, these general guidelines are a good starting point for success.

SPS require stability and are generally not well suited to new reef tanks or beginners.

Fish & Corals

Soft corals are some of the fastest growing corals, and easiest to keep. Most LPS (large polyp stony) corals are also relatively easy to care for and can tolerate a wide range of tank parameters. SPS (small polyp stony) corals are more difficult to care for and require a lot more input and planning to achieve long term success. Lighting and flow requirements also need to be considered for each specific coral. For instance, some zoanthids need high lighting to grow, and SPS corals may change color dramatically in different lighting settings. I once had a dark green chalice that went bright red in high lighting. Some planning is needed before you add corals to your tank.

There are also limitations on the type and number of fish you can keep. The more fish you keep, the more waste there will be, which will raise nitrates and phosphates. This means you’ll need to do larger and more regular water changes. If the fish you keep in your tank foul the water faster than you can keep up with water changes to maintain low nitrate and phosphate, you’ve overstocked your tank. If you’re not clear on your systems limitations you could end up with an algae issue or coral recession. But it’s also important to think carefully about what type of fish you want to keep. A tang of any sort will quickly outgrow a 40 gallon reef tank, and a mandarin goby’s feeding requirements will be extremely difficult to satisfy in a new or small reef system. Researching the requirements of each and every animal you intend to keep is vital to a successful reef tank.

Think Ahead, Way Ahead

There are a lot of considerations when creating a fish list for your reef tank. How big does it get? (Tangs get very large). Is it aggressive or predatory toward other species? (Many a shrimp have been lost to a hungry wrasse). Is it territorial? What does it eat? (Mandarin gobies are notoriously difficult to feed). Will it get enough of that food source in your system? Does it require a sand bed? (Many wrasse sleep in the sand). Is it a sand sifter? (Some wrasse and gobies will cover your corals in sand while they search for food). Thinking these things through and researching these creatures ahead of time will help you to avoid issues later on.

Mandarin Gobies are very hard to feed and spend their time searching the rockcape for ‘pods and live foods.

As we mentioned before, there are some exceptions to the rules, but often it comes down to a specific set of circumstances created by the reef keeper. One reef keeper will tell you he has never been able to keep anthias or leopard wrasse, for example. While another will swear by them as the easiest fish to keep. This could be due to many factors; the size of his tank, the other fish he keeps, how many fish he has, the fishes feeding habits or schedules, when he added the fish and how they acclimated to the system, whether or not they were quarantined first, how many of them he has and so on. Researching all this stuff in advance takes time, so be patient. Ask successful reef keepers for advice and tips on your next coral or fish before you go to the store to purchase it. There are many different ways to keep a successful reef tank, but ultimately that success comes down to the decisions you make. Doing some important research in advance can help you to make good ones.