Rochia nilotica, common name the commercial top shell, is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.

[1] This marine species is widespread in the Indo-Pacific (from Madagascar, Sri Lanka, Andaman and Nicobar Islands, to as far east as French Polynesia, north to southern Japan and Hawaii, and south to Australia,[2] including New Ireland, New Caledonia, North Australia, French Polynesia, etc.).

Embryos develop into free-swimming planktonic marine larvae (trochophore) and later into juvenile veligers that drift with currents before settling on a rocky surface.

Methods of culture are still under assessment and development where experiments have been conducted in Vanuatu;,[11][12] Australia,[11] Indonesia[11] and Vietnam.

[13] Cage-based cultures have proven effective because they allow control of food and predators, both of which contribute greatly to the growth and survival of juveniles;.

[11][13] Other benefits of sea cages include lower cost, easy to construct and transport, manageability and the advantage of using existing water bodies.

Alternatives such as high density releases of small juveniles and over large areas are less expensive and are thought to be solutions that can reduce predation pressure[11] from fish species such as Choerodon cyanodus[11] and Diodontidae and crustaceans such as Mancinella tubercosa and Calappa hepatica.

[13] Seaweed and algae are the main food and these grow on the dead corals and rocks which may occur naturally at the cultured sites or collected from adjacent areas and placed at the bottom of the cages.

[13] It is recommended that for cages with juveniles sized >30mm, these seaweed-covered rocks should be replaced 2 to 3 times a month and cover over 50% of the area.

[13] Cage design is important in preventing escape of juveniles and entry of predators and also shading of algal and seaweed on rocks.

[12] Shifting sand and sediment deposition areas may smother foraging surfaces and need to be avoided when allocating cages;.

[12] Suitable release sites of trochus juveniles into the wild include unconsolidated coral rubble and areas where predators are absent.

[11] It is common that juveniles are placed upright inside a cover such as a reef crevice;[11][14] or under macroalgae[11] as a means of predator protection.