That's a very good point, fishymania, and one have not seen before.fishymania said:...... Either try to fish them out one by one or you can use a medication which will not harm your fish in any way but it will leave dead snails in your tank and if you don't remove them, they would make your water putrid.
In other words, he might as well just pick them out from the start. That way, if he misses any at least they won't be rotting in the water and he can get them at a later time.