I need to glue lava rocks to glass for a small shrimp aquarium. What's the best thing to use? It has to be non toxic for the shrimp and also waterproof.
Silicone sealant will work well in this situation. It's the same stuff that holds the sides of the aquarium together. You can find it in many forms in Home Depot or Amazon.com.
check out marinedepot.com They even have different color glues for all your aquarium needs.
Loctite super glue works wonders on everything.