Zebra Nerite

The zebra nerite (Vittina natalensis, also encountered under the older name Neritina natalensis) is many aquarists' favorite algae eater, and the reason is simple: it grazes algae and normally does not establish a multiplying population in a freshwater aquarium. 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. A single snail does not require a school.

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. 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 and check that the individual actually feeds. Alternative foods are worth trying, but their acceptance should not be assumed. 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 check mineral availability and shell condition; crushed coral is one possible buffering approach, but its suitability depends on the other inhabitants and the water you start with. 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 may lay hard white egg capsules all over your hardscape, but successful rearing in routine freshwater conditions should not be expected. The larvae need brackish or salt water to develop, so routine freshwater keeping does not provide a reliable route to raising young nerites. That means no population explosion, just a scattering of cosmetic white dots.