Zebra Nerite

The zebra nerite (Neritina natalensis, recently reclassified as Vittina natalensis) is many aquarists' favorite algae eater, and the reason is simple: it grazes algae all day yet will never overrun the tank. Native to the brackish-influenced coast of East Africa, it wears a glossy shell streaked with black-and-gold bands that vary from clean stripes to zigzags and dots. It stays small at around 2.5 cm, and a single snail is perfectly content on its own.

What makes it so useful is its appetite. Nerites scrape algae off glass, rocks, and leaves, and they are one of the few animals that will tackle stubborn green spot algae. They leave healthy plants alone and only touch dead leaves. The trade-off is that they can starve in a spotless tank, so once the algae thins out, offer an algae wafer or a slice of blanched zucchini. Because they come from coastal waters, they want a pH above 7 and mineral-rich, moderately hard water; soft water pits and erodes their shells, so add crushed coral if yours is low in minerals. Two habits to plan for: they climb to the waterline to graze the mineral crust and will walk straight out of an open tank, so keep a tight lid, and they do best with peaceful tankmates rather than puffers or snail-eating loaches.

Here is the quirk people don't expect. A zebra nerite will lay neat white eggs all over your hardscape, but they almost never hatch. The larvae need brackish or salt water to develop, so in a freshwater tank the eggs simply sit there. That means no population explosion, just a scattering of cosmetic white dots.