The Aquacultured Squamosa Clam, Tridacna Squamosa can be a good choice for a beginning saltwater aquarist. They are native to the Indo-Pacific coral reefs, and are found in deeper waters of 50-65 feet. It's a durable clam that is exceptionally easy to keep in aquariums. The Squamosa clam can reach a size of up to approximately 12 inches in an aquarium and much larger in the wild, reaching just over 17 1/2 inches but growing large is slow for Tridacna Squamosa clams. It will take roughly 60 years to reach 17 inches. The mantle color pattern is easily distinguished form other species. The mantle is primarily golden color or sometimes yellow in coloration. Occasionally there are spots in orange, green, or blue. Another characteristic are the large scutes or plates on the shell.
Clam Placement: While T. squamosa is most commonly found on hard substrates, placing on any substrate seems to work fine. Again, I've seen them living on rubble, sand, and muddy sand in the wild. Although Squamosa Clams are one of the hardier clams to keep in the home aquarium, they do have some special care requirements. The clam should be stable, but never placed in a restrictive crevice that prevents it from opening fully, and it should not be placed in an area of high flow. Too much current will cause the clam to close up, and the zooxanthellae inside the clam will not receive enough light and the health of the animal will deteriorate. In the wild, clams grow with the mantle perpendicular to the sunlight, so they should be placed perpendicular to the aquarium lighting, even though that may result in more of a side-on view for the aquarist. This ensures that none of the mantle loses zooxanthellae, as it is exposed to the light in its entirety. It is not unheard of for clams to move around if they are unhappy where they have been placed, and they should be observed carefully in case they propel themselves into an even more unfavourable position, such as on their sides.
Lighting:T. squamosa lives at relatively shallow depths where they receive intense light, so fluorescent lighting is a poor choice for anything other than rather shallow tanks, unless a specimen is placed high up on rock-work near the water's surface in a deeper tank. I would try fitting as many bulbs into a fluorescent canopy/fixture as possible at that, and mount the bulbs close to the water, too.
Some giant clams, like T. derasa and T. gigas in particular, may be able to get by at times with less light, or further down in deeper tanks, but you shouldn't take any chances with T. squamosa. Metal halide lighting or comparable LED system lighting is your best choice option, with standard 175 watt metal halide bulbs typically being sufficient for any small to medium size tanks. For deeper tanks you may need to move up to higher-intensity bulbs, though.
This might sound like a lot of light to many successful coral keepers, but that's because giant clams aren't corals. Corals are very simple organisms that have no real "guts" to speak of, while giant clams have all the organs you'd expect to find in more complex animal. Like the other species, T. squamosa has gills, a heart, a stomach, kidneys, and gonads, etc., so it needs far more calories than a coral needs to get through a day. I can assure you that it's entirely possible to have plenty of light for corals to grow very well, but still not have enough to keep a giant clam. Each individual clam has its own requirements at that, with some needing more light than others, even at the same size. To add, you cannot give a tridacna clam too much light as long as a specimen is given time to adapt to intense lighting, so it's better to err on the bright side than the dim side. Don't take any chances!
Water Flow: When it comes to water flow, these clams typically live where they're regularly exposed to strong currents and wave activity. So, they're quite used to strong, surging water motion. Thus, it's perfectly okay to expose them to a surging or turbulent flow, but putting a specimen in a spot where a pump blasts it with a strong, non-stop linear current is not recommended. Basically, what you need to avoid is putting a specimen anywhere that currents cause its mantle to fold upwards or over onto itself all the time, or an even stronger flow that makes a specimen chronically retract its mantle. On the other hand, it's hard to have it too slow as long as the water constantly flows over and around them.
Diet and Feeding: T. squamosa doesn't need to be fed anything as long as a specimen is kept under sufficient lighting in a well-stocked aquarium with several fishes. Again, all giant clams are very good at absorbing many of the nutrients they require directly from surrounding waters, and fish in the aquarium are the source of these nutrients. Basically, you feed the fish, then the waste they give off becomes a food source for the clams. So, as long as you have several fish and feed them well, there won't be any need to provide your squamosa's with any sort of food.
Tankmates to Avoid: Avoid any species which would be tempted to nip at the mantle e.g. angelfish, large wrasses, some butterfly fish. Avoid placing the clam too near to stinging corals, particularly those with long sweeper tentacles, and be sure that none of your corals shade out the clam as they grow.
Proper Water Chemistry: Proper water chemistry is important to all Tridacna Clams. Best to keep calcium levels 380 to 450 mg/L, alkalinity levels between 8 to 11 dKH, and the tanks magnesium level between 1280 to 1350 ppm.
Acclimation to tank: Slowly acclimate the clam to your water conditions (drip acclimatisation is best, over the course of around an hour) and then place the clam as low down in the tank as possible, gradually moving it higher over 2 week time periods. It is important that it is not moved repeatedly over less a period of time unless you absolutely have to. Clams have a lot of trouble adapting to changes in lighting and current as it is, and moving them over and over again in shorter time periods can prove very stressful.
Care Level: Excellent "beginner" clam species.