QUICK STATS

Care Level: Moderate
Invert Type: Tridacna Clam / Derasa Clam
Scientific Name: Tridacna derasa
Temperament: Peaceful
Photosynthetic: Yes
Placement: Sandbed / Stable Lower Placement
Lighting: Moderate to High / Strong Reef Lighting
Water Flow: Low to Moderate / Indirect
Approximate Purchase Size: Varies by Specimen
Approximate Max Size: Up to Around 16" in Aquariums with Long-Term Growth

BLUE STRIPE DERASA CLAM

The Blue Stripe Derasa Clam is a colorful variety of Derasa Clam, known for its striped mantle patterning, blue rim or blue accent coloration, and large, smooth shell structure. Depending on the specimen and lighting, it may show shades of blue, teal, turquoise, gold, tan, brown, cream, black, yellow, or orange across the mantle and striping.

This clam is scientifically known as Tridacna derasa and is one of the more hardy and forgiving Tridacna clam species available in the reef aquarium hobby. Compared with Maxima and Crocea clams, Derasa clams are generally more tolerant of lower placement and slightly less intense lighting, though they still require strong reef lighting and excellent water stability. In plain English, it is one of the “easier” clams, which still means it has standards and will silently judge your calcium.

Blue Stripe Derasa Clams are popular because they provide color, movement, filtration, and a natural reef-lagoon look. Their mantle expands beautifully under reef lighting, and the blue striping or rim can create strong contrast against warmer gold, tan, brown, or orange base coloration.

The Blue Stripe Derasa Clam is photosynthetic and receives much of its energy from light through symbiotic zooxanthellae. It is also a filter feeder and may benefit from phytoplankton or fine suspended foods, especially when small. Larger Derasa clams rely heavily on lighting but still benefit from a healthy, mature aquarium with available dissolved and particulate nutrition.

Derasa clams are generally peaceful and do not sting corals or fish. Their main requirement is space, light, stable chemistry, and protection from animals that may nip, pick, or harass the mantle. They are peaceful, not helpless decorative furniture, despite humanity’s urge to place everything like a collectible paperweight.

Note: Image is a representation of what to expect. The clam you receive may vary slightly in size, shell shape, blue intensity, stripe pattern, mantle coloration, rim color, and overall appearance.

AQUARIUM REQUIREMENTS

AQUARIUM SIZE

A minimum aquarium size of 50 gallons or larger is recommended for a Blue Stripe Derasa Clam, though larger mature reef systems are preferred. Derasa clams can grow large over time, so they should be placed in a system with enough open sandbed space and long-term stability.

While smaller Derasa clams may fit in smaller aquariums temporarily, long-term care is easier in larger systems. Larger aquariums provide better water stability, stronger lighting options, more calcium and alkalinity buffering capacity, and more room for growth. A Derasa clam is not a tiny impulse frag forever. It is a future dinner-plate-sized bivalve with a mortgage.

PLACEMENT RECOMMENDATIONS

Blue Stripe Derasa Clams are best placed on the sandbed or on a stable flat surface in the lower portion of the aquarium. Unlike Crocea and Maxima clams, which often prefer rockwork, Derasa clams are commonly treated as sandbed clams.

Sandbed Placement: Place directly on the sandbed where the clam can sit upright, open fully, and receive strong light.

Stable Base: If the clam is small or the sandbed is unstable, place a small flat rock, clam cradle, shell, or tile slightly under the sand so the clam can attach if desired.

Avoid Sharp Rock: Do not place the clam on jagged rock that can damage the byssal opening or shell base.

Room to Grow: Leave open space around the clam. Derasa clams can become large and may gradually shift position as they grow.

Do Not Force Attachment: Do not glue, epoxy, wedge, or force the clam into place. Clams need to orient naturally and should not be trapped.

Mantle Clearance: Make sure the clam can fully extend its mantle without being shaded, touched, or irritated by nearby corals.

Light Access: Avoid placing under overhangs, plating corals, dense branching coral, or anything that blocks direct reef lighting.

WATER PARAMETERS

Blue Stripe Derasa Clams require stable reef water chemistry. Stability is more important than chasing perfect numbers. Sudden swings in salinity, alkalinity, temperature, pH, or nutrients can cause mantle retraction, poor extension, bleaching, pinching, shell-growth issues, or decline.

Temperature: 76-80°F
pH Level: 8.1-8.4
Salinity: 1.025-1.026 specific gravity
Alkalinity: 8-10 dKH
Calcium: 400-450 ppm
Magnesium: 1250-1350 ppm
Nitrate: 2-15 ppm
Phosphate: 0.03-0.10 ppm

Derasa clams use calcium and alkalinity to build shell. As the clam grows, consumption may increase noticeably. Monitor alkalinity, calcium, and magnesium regularly, especially in smaller systems or tanks with other calcifying corals.

Avoid dirty water, but also avoid stripping the system completely. Derasa clams appreciate clean, stable, mature reef water with adequate nutrients and available trace elements. The goal is not swamp water. The goal is not sterile glass sadness either.

LIGHTING

Blue Stripe Derasa Clams need moderate to high reef lighting. They are photosynthetic and depend heavily on light for long-term health, especially as they grow.

LIGHTING RECOMMENDATIONS

Moderate to High PAR: A general target range of 150-300 PAR works well for many Derasa clams, with some systems keeping them successfully lower or higher depending on depth, feeding, and acclimation.

Start Conservatively: Start around 100-150 PAR if newly added, especially if the clam is small, freshly shipped, or coming from lower light.

Gradual Acclimation: Increase light slowly over several days to weeks. Sudden light increases can cause stress, bleaching, mantle retraction, or movement attempts.

Sandbed Lighting: Because Derasa clams are commonly placed on the sandbed, make sure enough light reaches the bottom of the aquarium.

Color Display: Blue striping and mantle contrast often show best under strong reef lighting with a balanced blue-heavy spectrum.

Too Much Light Too Fast: Signs may include mantle retraction, bleaching, fading, or the clam refusing to open fully.

Too Little Light: Signs may include dull coloration, stretching toward light, poor shell growth, reduced mantle extension, or long-term decline.

Do not assume “sandbed clam” means “low-light clam.” That is how humans turn reasonable care advice into a slow-motion calcium-dependent tragedy.

WATER FLOW

Blue Stripe Derasa Clams prefer low to moderate indirect flow. Flow should keep the mantle clean and provide gas exchange without blasting the clam shut.

FLOW RECOMMENDATIONS

Ideal Flow: Low to moderate, indirect flow across the mantle.

Avoid Direct Flow: Strong direct flow can cause the clam to retract its mantle, tip over, or remain irritated.

Avoid Dead Spots: Too little flow can allow detritus to collect around the shell, mantle edge, or sandbed.

Watch Mantle Response: A healthy clam should open fully and keep its mantle expanded. If it stays retracted, check flow, light, pests, and water chemistry.

Sand Management: Avoid placing where sand constantly blows onto the mantle. Repeated irritation can stress the clam.

Shell Cleanliness: Detritus and algae buildup on the shell can be managed with proper flow and a stable cleanup crew.

The goal is steady water movement, not turning the clam into a bivalve windsock. Reef keepers do love taking a calm animal and pointing machinery at it, for reasons scholars may never fully understand.

DIET

Blue Stripe Derasa Clams are photosynthetic filter feeders. They receive much of their energy from light through symbiotic zooxanthellae, but they can also filter fine suspended foods from the water.

PRIMARY DIET

Photosynthesis: Moderate to high reef lighting provides much of the clam’s energy.

Phytoplankton: Live or preserved phytoplankton may be beneficial, especially for smaller clams.

Fine Suspended Foods: Very fine particulate foods, microalgae blends, rotifers, and other filter-feeder foods may be used carefully.

Dissolved Nutrients: Stable, low-to-moderate nutrients can support overall reef productivity.

Calcium and Alkalinity: These are not foods, but they are essential for shell growth. Keep them stable.

FEEDING FREQUENCY

For smaller clams, phytoplankton or fine filter-feeder foods 1-3 times per week may be beneficial. Larger clams rely heavily on lighting but can still benefit from a mature, naturally fed reef system.

Avoid heavy target feeding directly into the clam’s inhalant siphon. It is a clam, not a mailbox. Broadcast fine foods into the water column and allow the animal to filter naturally.

COMPATIBILITY

Blue Stripe Derasa Clams work well in peaceful reef aquariums when protected from nipping fish, aggressive invertebrates, unstable placement, and shading corals.

COMMON TANK MATES

Fish: Reef-safe fish such as clownfish, gobies, blennies, wrasses, tangs, anthias, cardinalfish, firefish, and peaceful community fish.

Avoid: Fish known to nip clam mantles, including many butterflyfish, some angelfish, puffers, triggers, large wrasses, and certain filefish.

Invertebrates: Generally safe with cleaner shrimp, snails, and common reef invertebrates. Watch large hermit crabs, predatory snails, certain crabs, and anything that may irritate or damage the mantle.

Coral: Keep away from aggressive corals with sweeper tentacles or strong stings, such as torches, hammers, frogspawn, galaxea, favias, chalices, and hydnophora.

Anemones: Avoid placing near anemones that may move or sting the mantle.

Urchins: Large urchins may bulldoze small clams or knock them over if the clam is not stable.

Clam Neighbors: Other clams can be kept nearby if each has enough space, light, and flow.

BEHAVIORAL NOTES

Temperament: Peaceful. Derasa clams do not sting, chase, or attack other livestock. Refreshing, honestly.

Growth Pattern: Large, heavy shell growth with an expanding mantle. The shell becomes broader and heavier as the clam matures.

Sand Clam Behavior: Derasa clams are commonly placed on the sandbed and may release byssal attachment as they mature.

Coloration: May show blue, teal, turquoise, gold, tan, brown, black, yellow, cream, or orange striping depending on the specimen, lighting, and photography conditions.

Blue Stripe Appearance: Blue stripe or blue rim coloration can vary widely. Some specimens show bold blue accents, while others show subtler blue tones under reef lighting.

Mantle Extension: A healthy clam should open regularly and extend its mantle broadly.

Light Response: Clams can react quickly to shadows or sudden light changes by retracting. This is normal. It is also the clam reminding you that it has more light sensors than your impulse purchases.

Shell Growth: Healthy growth may appear as a lighter new shell edge along the margin.

Byssal Opening: Avoid damaging the bottom of the clam or pulling it from attachment. Damage to the byssal area can be serious.

Pyramid Snails: Inspect regularly for pyramidellid snails, especially around the base, shell scutes, and byssal opening. These pests can weaken or kill clams.

Mantle Pinching: Watch for pinched, curled, or uneven mantle extension. Causes can include pests, irritation, water quality issues, or disease.

Gaping: A wide, loose, or persistently open mouth can be a stress sign, especially if paired with poor mantle extension or fading.

Shading Risk: Do not allow fast-growing corals, algae, or aquascape overhangs to shade the clam.

Calcium Demand: As the clam grows, it may noticeably increase calcium and alkalinity consumption.

Handling: Handle by the shell, not the mantle. Never force open the shell or pull on attached tissue.

Placement Reality: This clam can become a stunning reef centerpiece, but it needs room, light, and stable chemistry. It starts as a cute striped bivalve and gradually becomes a calcium-powered living paperweight with taste.

ACCLIMATION PROCESS

This acclimation method helps reduce stress by gradually introducing the clam to your aquarium’s temperature, lighting, and water chemistry.

1. DIM THE LIGHTS

Turn down aquarium lights or place the clam in a lower-light area at first. This helps reduce stress while it adjusts.

2. FLOAT THE BAG

Float the sealed bag in the aquarium for 15-20 minutes to allow the temperature in the bag to equalize with the tank.

3. OPEN BAG, ADD CLAM TO CONTAINER

Carefully open the bag and transfer the clam and shipping water into a clean container. Handle the clam by the shell only. Do not touch the mantle or pull on the byssal area.

4. ACCLIMATE USING TANK WATER

Add small amounts of tank water to the container every few minutes for 30-45 minutes. Clams can be sensitive to rapid changes in salinity and water chemistry.

5. INSPECT THE SHELL

Before placing the clam into the aquarium, inspect the shell, base, and byssal opening for pyramid snails, eggs, damage, algae, or hitchhikers. Remove visible pests carefully.

6. DO NOT DIP UNLESS DIRECTED

Do not use standard coral dips on clams. Many coral dips are not appropriate for Tridacna clams and may irritate or damage the animal.

7. TRANSFER CLAM TO AQUARIUM

Place the clam upright on the sandbed or on a stable flat base in the lower aquarium. Discard the shipping water. Do not pour shipping water into your aquarium.

8. LIGHT ACCLIMATE

Allow the clam to adjust gradually over several days to weeks before increasing light intensity. Watch for mantle extension, color, shell growth, firm response to shadows, and signs of stress before making major placement changes.