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.
I usually try to buy anything I need for my aquariums at the same store that I purchase my fish so I know it is the correct/safe stuff to use. It may be more expensive there but you can check names and then look for the product at regular stores.