They may not be interested in the snails due to their size, personally I would still put some mts in there as they are very useful. If they get out of control you can always remove them by hand by putting some lettuce or cucumber in the tank and turning off the lights, they will swarm all over it and then you can simply remove it (& the snails).I have 3 baby clowns, the 2 largest are about 2", I got the 3rd recently and he is still about 1"