Derasa Clam

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Species group:

Other common names: Southern Giant Clam, Smooth Giant Clam

Scientific name: Tridacna derasa

The basics:
The Derasa Clam is among the hardiest and most colorful of the larger clams, but it will outgrow smaller aquariums very quickly. Those in the trade are commercially cultured, and so do not impact wild populations.

The Derasa Clam is found in the Indo-Pacific region and along the Great Barrier Reef.

Appearance / health:
The mantle (visible portion of the body wall) may be a combination of orange, black, yellow, blue and white, and is marked with variable stripes, blotches and spots. The Derasa Clam may top 61 cm (24 in) in shell length.

The Derasa Clam will lose its brilliant coloration and fare poorly if not provided with large amounts of food and strong lighting, but with proper care is among the hardies of all aquarium Molluscs.

Behavior / temperament:
In order to support its rapid growth, the Derasa Clam will often remain partially open and feeding. It will not harm tank-mates.

The Derasa Clam grows very rapidly, and may triple its size within 12-18 months. Adults should be housed in a 75 gallon or larger aquarium. This clam also requires powerful, marine aquarium-specific lighting so that the nutrient-producing symbiotic algae which it hosts can thrive. The water should be well-oxygenated via moderate currents, ammonia and nitrite-free, and in the temperature range of 22-25.5 C (72-78 F). Crushed coral, sand or aragonite may be used as the substrate.

The following water quality parameters should be maintained for Derasa Clams: Salinity: 1.020-1.025; pH: 8.1-8.4; Alkalinity 8-12 dKH; Calcium 300-480 mg/L. Strontium, iodine and other trace elements should be added as suggested by the product manufacturer.

In addition to the nutrients provided by symbiotic algae, Derasa Clams require enormous amounts of liquid plankton formulas designed for use with filter-feeding marine invertebrates.

Clam larvae (veligers) are planktonic for several weeks. Captive breeding is rare in home aquariums, but common on commercial clam farms.

Written by Frank Indiviglio

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