As for a good epoxy that bonds well underwater, I still haven't found one (although its not like I have been throwing around cash to try to find one either
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Clownfish hosting is almost by chance. I know that certain types of clownfish prefer certain types of anemones, but clownfish are even known for taking xenia and even hammer corals as hosts too. Best you can do is find out which type of anemone your clownfish prefer and get one. Even better is to buy a clownfish with its host anemone from a store (although you don't often get the chance to).