Invertebrates Mollusks

Few Mollusks are found in aquariums, and they are not often available commercially. Among the gastropods, the cowries, well known to collectors of shells, can be kept in captivity. Some fish may nibble the "mantle", the part of the animal's body used outside the shell. Of course, in the event of any danger the animal retreats into its shell.

This cowry has withdrawn its mantle into its shell.

Hobbyists enchanted by the beauty of this shell can put a specimen in a tank containing small Pacific fish (Gobiids, Blenniids, Grammids, Pseudochromis, for example). In the bivalve group there is the famous giant clam, which can sometimes grow up to a length of 1 m in the wild, where it feeds on vegetal plankton. Some smaller species can be acclimatized in an aquarium. However, these animals are only recommended for experienced hobbyists.

Certain species of mollusks can be kept with fish, and sometimes with other invertebrates, so they are popular among hobbyists.

Gastropods
The species found in the aquarium trade are mainly carnivorous and feed on mussels or fish. There are others which graze the algae on the decor.

- Cypraea

Cypraea tigris

The highly decorated shell of the Cypraea is much prized by collectors. In aquariums the porcelain-like shell is only visible when the mollusk is at rest; when they are active, it is covered by the mantle (the most external part of the body), containing the sensitive organs. Two species are sometimes found on the market, both with a carnivorous tendency: the tiger Cypraea (Cypraea tigris), over 10 cm in length, and the geographical Cypraea (C. mappa), which rarely exceeds 7 cm. They are mainly active at night.

- Other Species
Small gastropods can sometimes be introduced on live rocks; they are not difficult to keep, as they are herbivores. In contrast, the species belonging to the Murex genus eat by piercing the shell of other mollusks, so they can be fed small mussels, shelled or intact.

Bivalves

It is sometimes possible to come across small specimens of the giant clam (Tridacna genus) that can be fed on mussel choppy. Most species have Zooxanthellae on the outer part of their mantle, and they must therefore be placed close to a strong light source. Giant clams are demanding as regards water quality.

Generally speaking, they need a certain amount of protection, nevertheless, they can be sold legally, although they are rarely found in the aquarium trade. Those that do appear on the market are mainly raised in tropical areas - and they are expensive. Size: 5-25 cm.