What are Coral Frag Plugs?

Coral frags are as diverse as the corals they are taken from. Likewise, the options for plugs, the attachment points for said coral frags, are nearly as numerous. Depending on the type of coral you are looking to propagate, there is a wide variety of options to suit your needs.

Plug Materials

The two major materials used for coral plugs are ceramic and aragonite. These can be shaped into a variety of shapes and sizes.

• Ceramic: Ceramic materials are classified as both inorganic and nonmetallic, and are typically formed out of clay or stone. It is also non-reactive, and heat resistant.
• Aragonite: Aragonite is a carbonate-based mineral. Unlike ceramic, it is formed by biological as well as physical processes. Aragonite sand is a common substrate for reef tanks.
• Live Rock: Small sections of live rock can be used as plugs or attachment points for coral frags. These can then be placed in a reef exhibit, provided they are placed in a location where they can be secured.

It’s all about style: Size and Shape

Both ceramic and aragonite plugs can be found in a variety of shapes and styles. The traditional “plug”, typically a round disk with a short, cylindrical base is common, allowing ample room for frag attachment. Disks are essentially the same, though they are missing the cylindrical base. A flat surface on both the bottom can be useful when gluing the plug into display live rock or setting on the substrate of your tank.

Tiles are also flat, and come in a variety of shapes and sizes. Both tile and rubble, often bits of recycled coral skeleton or pebbly substrate, can be used to settle mushroom corals, provided their base is left intact from a transfer event. In good conditions, corallimorphs may naturally attach to the substrate within a few days.

Frag Racks and Rocks: The Inbetween

So consider the following situation: after fragging a coral, you are unsure of where you would like to place it in your display. Many coral keepers house frags on frag racks, trays of plastic egg crate or similar materials that keep frags off the bottom of the tank and in proper water flow while in transition.
Another option is frag or plug rocks, which are designed with appropriately sized holes to allow frag plugs to rest and be secure within the rock. This eliminates the potential challenge of securing a plug to an uneven surface.

A note of caution: when keeping coral frags of different colonies, and especially of different species, keep a watchful eye on the posture of the tissues and polyps, and for the presence of sweeper tentacles. If two corals are placed in too close of proximity, these sweeper tentacles, which contain stinging nematocysts, can damage the other’s tissue and in some cases lead to a coral’s death.

Frag plugs are an important and easy way to keep track of coral frags. With the correct selection, they can be used for all types of corals. They can be found in all sorts of shapes and sizes, and in a few different materials to meet your needs. Frag racks and plug rocks are useful to keep many individual frags organized, but require you to keep an eye on interspecific relations, including battles for space.