That is very different from snailspecies to species. Some snails are mostly vegetarian, but others (most spp.) will eat anything from dead fish to algae and bacteria.... and eggs, if they get the chance at it.
There are even snails that are predatory. (Well, I know of predatory saltwaterspecies anyway)
Bottomline from my POW: If you don't know the caracteristica of your snails, I would advice you to just start picking them up by the numbers until your eggs are hatched (Very boring... I know.... ZzZzZz)
When I do a waterchange and have a snailproblem, I will just vacuum every snail I can see. Takes time, but what can you do.
Welcome to this magnificent site, btw
