Snails have a bad reputation earned entirely by the wrong species arriving uninvited. The ones you choose on purpose are among the most useful animals in a planted tank.
Nerites: the ones that cannot overrun you
Nerite snails are the best algae grazers we sell and they cannot reproduce in freshwater — their larvae need brackish water to develop, so a nerite population never explodes. They will lay small white eggs on hardscape, which are harmless and which nothing will hatch from. They also climb, so keep a lid on: a nerite that goes over the rim will not come back.
Mystery snails: the pet ones
Mystery snails get to golf-ball size, come in gold, ivory, magenta and blue, and are genuinely interesting to watch. They do breed in freshwater, but above the waterline in obvious clutches you can simply remove. They need calcium in the water for shell health — our hard San Diego tap water suits them well — and they will eat soft plant leaves if underfed, so feed them.
A pest snail bloom is a feeding problem
Bladder and ramshorn snails arrive on plants and multiply to match the food available. A population explosion is not a snail problem, it is a signal that you are putting more food in the tank than the fish are eating. Cut feeding and the population falls on its own. Assassin snails work too, but they are treating the symptom.
Copper
Same warning as all invertebrates: check every medication and fertilizer label. Copper kills snails at doses fish tolerate without trouble.
See also shrimp, invertebrate food and plants.
