How To Glue Coral To Live Rock Underwater (Reef-Safe)

Image Credit: Bulk Reef Supply via
Image Credit: Bulk Reef Supply via

How To Glue Coral To Live Rock Underwater (Reef-Safe)


Every great reef aquarium needs some coral but they don’t just latch onto live rock themselves right away. An aquarist needs to put in a little work if they want their coral frags to attach to their live rock. To do that, you are going to need something to make sure that the process goes off without a hitch.

Your tank setup matters

How you decide to place your corals will depend on the needs of your corals and the design of your tank. That is because, though we try, the environment inside your tank is not entirely equal. There are pockets where light is stronger or weaker. There are spots where the flow is flowing much faster than other spots. All these tiny variables will affect where you can place your corals. Of course, if your tank is not already set up, you can plan for your coral’s introduction much earlier and design your lighting, flow patterns, and future growth patterns.


If you are using a lot of SPS corals, then you will need to place these corals where the lighting is strongest in your tank. This means you should consider the middle of the tank where most of the lighting meets together as one of the more lit areas of your tank. Of course, that doesn’t include areas in overhangs that might be in the middle of your tank. The higher up you go, the brighter it becomes so corals with strong light needs should be placed here. On the other hand, the outskirts of your aquarium usually have very little lighting so it is best to put corals that don’t need much lighting in these spots. Ultimately, you should purchase a PAR meter to get a better idea of where to place your corals. It will give you an accurate reading and will help give you a more informed decision rather than guessing.

You can tell whether your coral is getting too little light if it’s losing its color and becoming brown or white. A coral that is receiving too much light will shrink away and generally look uncomfortable but if you see this you can simply move the coral somewhere else. You do have some time to find the best placement for your corals as they can withstand not enough lighting for a decent amount of time.

Flow patterns

Place your SPS corals where the flow is much higher and the soft and LPS corals where there is less. That means soft and LPS corals shouldn’t be against a powerhead. Often the best places for these corals will be on the outskirts of the tank. After you have placed your frags, it will be a good idea to monitor them to ensure they are not in an area where the flow isn’t appropriate for them. Watch for signs of distress like if the bulbs are retracting or if they are sagging. These can be signs that the coral will need to be moved to a different place or the flow altered to meet their needs.

Growth patterns and spacing

Knowing how your coral will grow over time can make a big difference in how you place them in your tank. If you know that your coral will grow upwards in a certain way but requires a lot of lighting make sure they don’t begin to grow away from the light and that they have the room to grow in the first place. So before you start applying super glue gel to your live rock, make sure that that the frags will have the room to grow appropriately. Always think about the future direction that your tank will take as it develops and matures.

How to prepare coral for mounting

If you already have a coral that you want to use but isn’t prepared, you need only cut off a small piece to prepare for mounting. The piece of coral that you remove will be called a frag and this is what we are going to be gluing to different rocks in the tank. The frags that you glue on your live rock will begin to grow into their own coral.

How you remove your frags will depend on your own personal preference as well as the type of coral that it might be. Make sure to pick a method that best fits the type that you are working with.

Cut off

You can cut frags off corals with specified cutters made just for that or you can reach into your garden shed and see if you have any pruners. The pruners will work well with corals like Hammers and Torch.

Break off

Often you might even find that you accidentally broke or you can purposely try to this as long as the coral can handle it. The corals that this method works best with are Echbinophyllia chalice and Seriatopora. Remember to wear thick gloves if you try this and use your thumb and forefinger to deliberately break off a piece.

Saw off

A bandsaw will work wonders for tougher corals like Catalaphyllia and Goniopora corals. This is a precise method and works best for a large variety of corals but it is often a more expensive option if you don’t already own one.

MCR Safety Gloves
Oceans Wonders Cutter
Gryphon AquaSaw

Frag plugs, do you need them?

If you bought your frags directly from the store (which you will have if you don’t have corals yet) then your frags probably came with plugs attached. A frag plug is meant for shipping and sale display purposes but they don’t look great in the reef tank. The best thing you can do is to carefully cut the plug off completely or remove as much as you are comfortable doing. It will make the final product a lot more attractive than leaving the plug jutting out of the live rock.

How to mount corals

Now that you have a decent idea of where you want your coral to be placed, the next step is safely securing them inside your reef tank. To do this, you will need a few things. The option that you choose will determine how easily it will be to attach the pieces.


    • If you are going with epoxy, try to be conservative with how you set it. The epoxy will stick easily so use the grooves of your rocks to help hide the substance from view. The coral can attach to the epoxy directly.
    • You should work with the standard epoxy outside the water and once it’s ready apply it to the desired rocks for your coral to stick to. Underwater the putty can quickly fall apart and become a pain to work with.

Quick Setting Epoxy

    • You can also use a quick setting epoxy to attach your frags as it might make the job easier. The putty can be white so it might be good to mix it in the standard epoxy to get a color more closely resembling your rocks.


    • Superglue comes in a lot of different varieties and consistencies. A thick gel will let them retain their shape in the water better than the thinner glue. The glue will develop a bubble underwater that will allow it to be manipulated like putty but for it to stick effectively, the bubbles will need to be pierced.
    • If you use the putty-like glue bubble as a plug to the rock, it will probably be cut open by the sharp rock edges, effectively attaching to the rock. Follow that up with a sharp piece of coral to pierce the other side of the glue-bubble and you have secured your coral.


You might consider attaching the super glue gel to the frag outside the water. Make sure the piece is completely dry and then stick the glue to the underside of the frag. Put the piece in the desired location in the aquarium and it should easily attach.

Instant Ocean HoldFast
Tunze Coral Gum Instant
BSI Super Glue Gel

The benefit of super glue gel

Super glue gel is a widely acceptable adhesive to use for aquarium-related work. It is entirely reef safe because of the nature of the glue. The science related to the chemical makeup of glue is the reason behind this safety. One of the ingredients in glue is Cyanoacrylate which causes the glue to become more firm in its structure when it comes in contact with water. Don’t worry the firm bubble still retains its ability to glue things but it prevents the glue from floating around in the tank causing a potential mess. As long as your glue has Cyanoacrylate in it, it is a perfectly good reef glue.

Super glue gel specifically is preferred over regular super glue because it is much easier to manage compared to the liquid form. Remember that gluing dry objects is much more manageable than gluing underwater but it can be done. You need to use a decent amount from the tube, about the same that you might use for putty. Then remember it needs to be pierced for its gluing properties to really work so attaching to rocks is easy enough but it is when you need to apply the coral carefully.

Consider making a hybrid of epoxy and super glue

If you want to have an extra secure structure, try attaching the epoxy putty to the rock and then super glue the bottom of the frag. Then press the frag into the rock and it should dry within 2 minutes. This method helps to form an extra-strong bond that will dry quickly and with little noticeability. It works great for attaching to rocks quickly and cleanly.

What do I do if I messed up applying the epoxy?

You accidentally took too long to put your piece in the epoxy in your rock and it became hard and unusable. Now what? Well, it is actually really easy to dig the epoxy out of the rock and try again. Use a screwdriver or other long metal object to carefully remove the epoxy from the rock. Just be mindful that you don’t hit other pieces that might be setting or other objects in the tank like your live rock.

The only issue you might run into is if you spent too much time playing with the putty underwater and it began to come apart. Don’t waste time playing around with it. Make sure you know where you want to use the putty, ready it, and apply it. Putty that falls apart underwater can make your water quality a little cloudy and you don’t want to deal with that when you are trying to glue frags.

Adjusting lighting after you have already superglued the frags to rocks

The most efficient way you can go about adjusting the lighting at this point would be to buy the PAR meter we mentioned earlier. Hold the meter at the various frag mounts and start recording what the readings say. Once you have formed a general idea of the layout of light in your reef aquarium, you can start to adjust the lighting appropriately.

There might be some cases where the distribution of your corals will prevent you from simply adjusting the lighting. In these cases, you will need to make a judgment call and remove the frags that are contradicting the needs of others around them.

Final thoughts

Displaying corals is the best lesson in seeing how so many pieces of the saltwater tank’s ecosystem interconnect with one another. Not only must you plan the location of the corals based on their individual growth patterns but you need to consider the flow and lighting of the entire reef aquarium. Make sure you put ample putty to hold the bit of coral to the live rock but remember you need to move with purpose to avoid your putty or glue from drying out. Mounting your corals can be a really easy task; the tricky part is ensuring they are placed in places that will benefit their health.

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