Genus = Hippopus Species = Hippopus Common name= Hippopus clam Size and growth rate H. Hippopus can grow to a maximum size of about 19". These clams have been reported to grow as little as 4cm and as much as 7cm per year. Location and geographic range Hippopus clams are often found in shallow reef flats on sand in grass or on muddy surfaces. They can range in depth from the intertidal zone and usually less than 6 meters deep. They range from the Eastern Indian Ocean from Myanmar east across the Pacific to the Marshall Islands, Tonga, and Fiji. Attachment to substrate H. Hippopus uses their a byssal organ that secretes the sticky threads that will attach it to the substrate while in the juvenile stage. This helps keep the clam from being swept away. As the clam gets larger they rely on their size and weight to hold them in place. Lighting and flow requirements H. Hippopus are one of the most light demanding of all the giant clams. I recommend metal halide or T5 with individual reflectors. Giant clams are found on reefs that usually have SPS corals, flow should be moderate to high. Just be sure that the mantle isn't being held over un naturally because of too much flow. Coloration The Hippopus clams can be found in just a few colors. The vast majority are yellow, brown, or green with white, cream, or golden splotches and or thin stripes. Reef compatibility Giant clams are found among the reefs of the world and are compatible with most reef safe animals. Although there are some reef safe fish that are not clam safe. These include: Angelfish, some Wrasses, Blennie's, Eels, and some shrimp. Conclusion and comments. H. Hippopus are very uncommon to the aquarium industry. They are being farmed by many clam farms throughout the world and are being used to restock the worlds reefs from stress due to over fishing. It is my personal opinion that if you intend to keep a Hippopus clam you should have an aquarium of 50 gallons or larger with very good lighting. They can be kept in smaller tanks but they rapidly outgrow them.