How to fix rockwork in water?

[santeeeyyy]

Hey so my rock work for my original tank just broke into its original pieces. What would work best to attach it while it’s under water. I recently moved my tank so it broke in pieces and I just have one piece of rock from my original cycle in my tank

 

[TX_REEF]

Use epoxy putty, I use two little fishies brand, coralline red instead of white which sticks out like a sore thumb: https://amzn.to/48TetVt .
After kneading an appropriately sized ball of epoxy, apply a small glob of cyanoacrylate (I use seachem coral glue: https://amzn.to/3tGBmMZ )to each spot on the putty that will contact rock. This will ensure a strong and lasting hold between the rock pieces.