Giant clams from the Tridacna genus have become very popular amongst reef aquarium hobbyists for their vivid colors and beautiful patterns. However, commonly missed are the additional benefits these clams provide, beyond their aesthetic value. Of the Tridacna genus there are several species of giant clams that are commonly available in the reefkeeping world:

• Maxima – Tridacna maxia
• Crocea – Tridacna crocea
• Squamosa – Tridacna squamosa
• Derasa – Tridacna derasa

While these giant clams will add a bright splash of colors to any reef tank, their ability to filter out nutrients in the water column is often overlooked. As any hobbyist knows, nutrients in an enclosed reef tank tend to build up over time and become a concern even at pretty low levels. These nutrients, if left unchecked, may lead to problems with various forms of nuisance algae, cyanobacteria, and less then optimal health amongst reef tank inhabitants. These giant clams actually remove nitrates and ammonia from the water column, and can lead to better water parameters. Giant clams achieve this by continuously circulating water through their internal organs and consuming nutrients and plankton. Along with zooxanthellae within their syphonal mantle (the fleshy, colorful part of the clam), Giant clams use these nutrients to assist in the photosynthetic process.

The major advantage a clam has over other biological filtration is that it removes the ammonia BEFORE it is allowed to enter the nitrogen cycle, and therefore prevents nitrates from being formed. This action results in lowered nitrates and bioload.

Naturally, we do not suggest attempting to use these clams as your main form of filtration. The use of a refugium, protein skimmer, as well as chemicals is recommended in assisting any hobbyist with their goal of excellent water parameters. However, these giant clams can certainly increase both stability and biodiversity in your reef tank.

Photography by Felicia McCaulley

Felicia has been keeping aquariums since the early 90s and has a keen interest in taxonomy, aquaculture, and seahorses. she is the former Liveaquaria Diver's Den photographer and now works for Philadelphia area's largest aquarium specialty store The Hidden Reef.