Frag Tank: Setup Tips & Best Tanks for Ideal Coral Propagation

One of the great things about keeping live corals is the ability to propagate new colonies.

You’ve probably heard about “fragging” stony.

The process involves cutting off small pieces of living coral (frags) from a large coral and using them to start new colonies.

We won’t get into the details on how to frag here. But before you jump into the world of fragging, you’re going to need the proper aquarium setup to grow out the coral frags.

Why Use a Frag Tank?

Green Acropora SPS coral in a frag tank

Aquarists and commercial coral farms have tested and refined a simple method for propagating LPS and SPS corals in aquariums.

Most coral frags are relatively small. The frag is simply a small piece of living stony coral cut from the main colony.

The frags are glued to a ceramic frag plug to make it easy to move and position the frag without actually touching the delicate colony.

A dedicated frag tank makes propagating live corals much easier. Here’s why:

  • The frag tank can be much smaller than the main display aquarium.
  • Water changes are easier to make.
  • The frag tank is shallow and easier to work in.
  • You don’t need a complex filter system.
  • You don’t need a large lighting system.

Frag tanks have ideal water quality

Sure, you can position frags in your reef tank or use a frag rack inside your tank.

But with a dedicated frag tank, you won’t have the build-up of nutrients like phosphate and nitrate and dissolved organics that make coral propagation more difficult.

That’s because a frag tank doesn’t contain fish and other non-coral marine life.

A display aquarium is a home to countless microbes, plankton, and micro-invertebrates, along with fish and other non-coral inverts.

All of this marine life contributes to the bioload in the water.

With a dedicated frag tank, you’ll experience:

  • Less algae growth
  • Cleaner water
  • Lower nitrate and phosphate
  • Less chance for coral disease problems.

Tips on Setting Up a Frag Tank

LPS and SPS corals getting propagated in a frag tank

The main thing to remember is that a frag tank is all about growing out your corals, not looking like a beautiful display aquarium.

The size of the tank depends on how many frags you plan on growing and the amount of free space in your home.

Purpose-built frag tanks are usually relatively shallow but have a large footprint for holding a lot of frags.

However, if you’re not planning on “farming” a lot of corals, there are plenty of aquariums that will work for fragging.

Here are some tips for a frag tank:

  • The tank can be as shallow as six inches/15 cm. You don’t need a deep aquarium.
  • Ensure the length and width provide enough room for egg crates and racks to support and separate the frags.
  • Like any aquarium setup, make sure you have an electric outlet nearby.
  • Locate the tank out of reach of curious children and pets.
  • You don’t need an enclosed top. Most fraggers suspend lighting above an open aquarium.

Frag tank filtration

There are several approaches to maintaining a frag tank.

Depending on the size of the aquarium, some reef aquarists simply make water changes every few days.

They siphon out debris and uneaten food and add freshly-made saltwater.

Aquarists with large or heavily-stocked grow-out tanks will use a power filter, canister filter, or sock filter to remove suspended debris.

A protein skimmer is sometimes used when the coral frags are heavily fed.

If you use a power filter, GFO and activated carbon will help keep the water cleaner and lower algae-promoting nutrients.

Water movement

Corals and frags need good water movement to carry away waste and bring oxygenated water and food to the polyps.

You don’t need to blast the frags, just continuously move the water throughout the tank.

A submersible flow pump or gyre pump will provide gentle water movement across the frags.

Zoa and mushroom corals prefer less intense movement than stony corals.

Lighting the frag tank

Coral frags will need lighting just like the tank they came from. The light energy is necessary to produce new tissue through photosynthesis and lay down coral skeleton.

Even soft corals need good lighting to heal up and grow. T-5 fixtures or multiple LED strips are popular lighting choices, especially with smaller, shallow frag tanks.

Best Tanks for Coral Fragging

Colorful Chalice LPS coral on frag plug in a frag tank

Now that you’ve got a good idea on how to set up your frag tank, it will be easier to decide on a frag aquarium design.

While there are a variety of designs to choose from, we’ve selected the most frag-ready aquariums in our review.

1. Planet Aquariums

Planet Aquariums was founded by two former aquarium builders from Oceanic.

Their expertise shines through with their approach to custom aquariums. Planet Aquariums has taken the complexity out of designing your own tank.

Simply select the basic design and select your options from the drop-down menus. It’s that simple.

You can select a basic frag tank or add extra features like an overflown silicone color and background.

Your aquarium will be made in Texas and shipped to your home.

2. Coast To Coast Custom Aquariums

CTC is a custom aquarium builder located in Toms River, New Jersey. They offer a variety of hand-made aquariums in virtually any size.

The company does not advertise standard aquariums or off-the-shelf designs like other dealers.

You’ll have to contact them to discuss your project. CTC experts will guide you through the process of selecting the design and size of your tank.

They offer three types: Precision, Eurobrace, and Rimless construction.

CTC can make any type of frag or display tank you can imagine.

3. Innovative Marine Lagoon 25 PRO

Innovative Marine has a reputation for manufacturing high-quality aquariums.

The Lagoon 25 Pro is an all-in-one (AIO) system with a built-in filtration system. Water passes over the overflow and into the integrated filtration chamber.

The filtration system includes the Mightyjet DC pump, Customcaddy media rack, and PurityPack filter media kit.

The aquarium is low enough for fragging and but deep enough to spread out a variety of frags across the bottom of the tank.

The aquarium is built with low iron glass with beveled and polished edges.

4. Zoomed

They are best known for their reptile products. Zoomed has a 50-gallon “lowboy” tank that works for fragging.

It’s a no-frills basic aquarium, but it holds fifty gallons and is very shallow while being long and wide.

It is easy to work in, and you can hang a filter on the side for water flow and filtration.

5. Deep Blue Professional

Deep Blue Aquariums, now associated with Sepora aquariums, is a maker of a unique line of frag-friendly aquariums.

Their frag tanks are shallow but long and wide. So you have a choice between a basic undrilled aquarium or a reef-ready aquarium complete with a corner overflow system.

Tank size ranges from 40 to 80-gallons. Some models are rimless designs, while others use a sturdy black injection-molded frame.

6. Aquarium Industrials

Also known as Aquarium Masters, AI offers specialty fragging aquariums.

Available in 60 or 80-gallon sizes, the frag tanks are perfect for assembling your fragging system.

The aquariums are constructed of distortion-free glass with diamond polished edges.

The plastic rim allows you to use hang on back power filters and lighting systems. The tanks use black silicone to seal the edges.

7. Glass Cages

Located in Dickson, Tennessee, Glass Cages has been making customized aquariums in the US since 1998.

The company can build an aquarium to your specifications. Options include black or clear silicone, euro or traditional bracing, overflows, and special corner guards to strengthen the tank.

The tanks come with leveling pads and can even be wrapped with a custom vinyl background.

Frag Tank Q&A

Do I need to cycle the frag tank?

Coral frags will seed the tank with beneficial bacteria.

Careful feeding, especially during the first month, will greatly reduce the chances of an ammonia or nitrite problem.

Test your water once a week to be sure the water contains no detectable ammonia and nitrite.

Where should I set up the frag tank?

Some aquarists have room to place the frag tank near the display aquarium. This makes it easy to transfer corals between the tanks and perform maintenance.

You may prefer to have the frag tank out of sight. It can be set up in another room or basement, as long as the tank has a steady temperature and proper lighting.

Do frag tanks need fish?

While there are reef-safe fish, most fraggers only keep corals in the frag aquarium. Many fish will peck at the delicate coral tissue, especially around a newly fragged piece.

Fish also need to be fed, which increases the solid waste and ammonia in the tank. It is best to keep the fish in the display tank.

Do I need a heater?

The coral frags should be treated just like the parent colonies. This means the water temperature should be kept at the same level as the display aquarium.

Can I put the frag tank outside?

Universities and research centers located in warmer climates have experimented with outdoor frag tanks.

If you place the frag tank outdoors, the water must remain in the proper temperature range.

The water cannot cool off at night or get too hot in the daytime.

You may need to use some type of shade cloth to reduce the intensity of the sunlight on the frags. Too much sun can exceed the coral’s lighting needs, slow down growth and “burn” the corals.

Can I use sand in the tank?

It is best to use a bare aquarium when fragging. This makes it easy to clean the tank and prevents the accumulation of debris in the sand.

How do I minimize algae growth?

Algae need light and nutrients to thrive. Since the corals need the same lighting, the best approach is to limit nutrients in the water.

Don’t over-feed the coral frags. If you do feed heavily, siphon out uneaten foods and make water changes. This will limit the nutrients in the water and keep algae under control.

Final Thoughts

Whether you want to start fragging with a plug-and-play aquarium or order a custom aquarium, today’s manufacturers make it easy.

Innovative Marin’s Lagoon AIO tank is ready to run. Just add lighting.

If you don’t need the built-in filter, Zoomed’s Low Boy 50-gallon tank is a good base to build your own fragging system.

For smaller fragging tanks, be sure to check out Aquarium Industrials.

Maybe you need something special for your fragging project.

CTC will work with you to design it just the way you like. Then, they’ll crate it up and ship it directly to you!

If you have any questions or comments, please post them below.

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