Neritina gagates is a species of freshwater and brackish water snail, belonging to the Neritidae family. The snail measures up to 22 millimeters. Neritidae are distinguished by their thick, rounded shells with sunken spire. Their operculum (lid like structure located at the shell opening) is calcareous with a small protruding inner peg.
N. gagates is native to the coast of South Africa, Madagascar, the Comoros, the Seychelles and the Mascarene islands. The species is typically found in streams near tidal influences, or on rocks with moderate current. Neritidae are active at night and graze on macro-algae. They lay small oval white egg masses in rock crevices.
This species is common throughout its native range and is therefore listed as a species of ‘Least Concern’ in the IUCN Red List of Threatened Species. It may experience localized threats such as water pollution.
Freshwater nerites have become popular in the aquarium trade due to their grazing abilities, helping to keep tanks clean from algae.