Blue Tridacna crocea.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.

Within modern taxonomy, currently the "giant clams", bivalve molluscs, are in the subfamily, Tridacninae, under the family, Cardiidae (the cockles), although some scientists still argue that these clams should be in their own family, Tridacnidae. The genus, Tridacna, holds the most common species within the marine aquarium trade, and aquarists usually refer to the "Tridacna clams."

Tridacna clams are broadcast spawners. By that I mean when they spawn, they spew out both sperm and eggs, first one, and then the other, into the water, and they're able to do that because mature giant clams are simultaneous hermaphrodites.

These eggs and sperm are microscopic, and if you're lucky or unlucky enough for this to happen in your tank, your aquarium will soon be filled with a milky cloud not unlike what happens when anemones spawn, and you'll have a tank emergency.

The home breeding of broadcast spawners is notoriously difficult, and for that reason--even though Tridacna clams are vanishing quickly in the wild--breeding has typically been done mainly by researchers, who have available teams of scientists and a lot of square footage to devote to the process in a laboratory or in the ocean.

Not only is breeding these clams difficult, but the clams take years to grow and mature. And some species of Tridacna clams live to 100+ years old in the wild.

There is, however, one hobbyist--and I use that term loosely--breeding giant clams. His name is Acro Al.

Acro Al is well known in saltwater aquarium circles first for Acropora coral propagation, which he has been doing for years, but also for breeding and farming Tridacna clams, previously considered impossible at home.


On a nondescript, tree-lined, suburban street in Perth, Australia, a young man tends to thousands of Tridacna clams. He has clams at every stage of growth from microscopic just-fertilized specimens to adults over a foot long.

Exactly how Acro Al is doing what he's doing remains shrouded in mystery. He was, however, kind enough to talk to me for this article and answer a few questions. So, I'll let him speak for himself.

Dallas Acropora that Acro Al is famous for.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.

First, tell me who you are and what you’re doing that is of such great interest to the marine community?

Allan van Zijl from Perth Australia, started in the marine hobby 2003, kept Acropora and began aquaculturing coral before moving to Giant Clams at home. Giant Clams have never been raised in a home/hobby-based environment, giving inspiration to DIY aquarium breeders.

Do you have a big professional space for your breeding? (I mean you’re not doing this out of your house, right?)

It’s all out of my house. All within a 250-square-meter-in-total strata complex unit, five minutes from Perth city and 20 minutes from the ocean.

Are you also breeding other sea creatures?

Yes, Acropora (staghorn) [coral], Trochus [snails], and Banggaii cardinals intermittently.

How many aquariums did you have when you started and how big did they get?

Started small [with] 200L, then expanded to 2x 6x2x2 aquariums.

Tell me about some of your early successes and failures with marine livestock?

Keen inspiration for Acropora, created my alias ACRO AL, began my own research into captive growth. Was susceptible to tank crashes early on when still learning. Mainly from overstocking issues.

Even experts have an occasional hitchhiker that does damage. Here, a wayward crab snacked on some baby clams.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.

Can you think of any individuals who encouraged or discouraged you along the way?

For the clams--great advice from Gerald Heslinga the godfather of Giant Clams.

When did your interest here turn into an aquatic business?

When I noticed a small Australia-wide market for a bit of fun and enjoyed the hobby so much.

When did you move over to clams?

2010, when I contacted Gerald from the huge clam operation that took place in the 70’s 80’s and 90’s in Palau at MMDC [Micronesian Mariculture Demonstration Center]. When I asked if breeding clams was going to be possible in a home environment he said “don’t wait another day! Thereafter providing a wealth of knowledge and support.

Why did you move over to clams?

Because of the beautiful colours and they are such a strange animal. Australia can not import clams from anywhere, so to selectively breed these colourful animals would be a niche market as there is no international competition.

Tridacna squamosa.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.

Are you using natural sea water?

Yes, always.

How far away from the shore do you go to get it?

20 km from home off a jetty in the harbour, 4000L at a time sucked up with a fire pump.

Do you treat the water in some way before using it?

No, only micron cartridge filtration when needed.

How big or old does a clam have to be to spawn?

It is said three years male and five for female.

When you acquire clams to breed, do you quarantine them?

No, straight from the ocean into tanks.

Do you medicate them with anything?


Ever have a problem with pyramidellid snails?

They are a real pain. They don’t worry adults too much but these snails can easily be seeded to a juvenile tank and cause significant problems if they are left too long. Regular transplanting and cleaning prevents an outbreak.

When you’re waiting for spawning do you keep several of the same species in one tank to try to, you know, have more genetic diversity?

Yes, of course, avoid self-fertilisation.

Are you trying to crossbreed or hybridize different species?

I have tried, and it fails.

Are you doing anything with Hippopus clams?

Not just yet, fast growing but very ugly, not a good candidate for ornamental purposes.

What do you feed tiny baby clams?

Nothing. It has been proven they do not need to eat to thrive at any stage up until adulthood. I have tried disproving this and various other things, but it is important to note that the work done by Gerald Heslinga and Tom Watson from MMDC, and also Rick Braley from ACIAR [Australian Centre for International Agricultural Research], still proves to be highly accurate, decades later.

How fast or slow do baby Tridacna clams grow?

For the T. maxima and T. crocea, you can expect 1mm per month for the first five months and then 1mm per week thereafter. I have not had success with other species yet, but T. derasa a larger species, has been shown to reach 5cm in about 1 year, half the time as T. maxima.

What species are you breeding?

T. crocea

T. maxima

Baby Tridacna crocea clams.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.

How many employees do you have?

I run the entire breeding operation by myself. Spawning, raising, grow-out, cleaning, water changes, problem solving, maintenance , advertising, taking photos, retail and wholesaling, and packing out the clams interstate. All Paperwork and licensing work!

Do you have any family members that help or work for you?

Yes, my lovely wife, Narelle, who mainly puts up with tantrums of a frustrated inland clam farmer.

Do you ship clams?


Where do you ship clams?

Interstate Australia-wide, and international is coming soon.

How do you ship clams?

Airport to airport in foam eskys according to seafood transport regulations.

Tridacna gigas, considered threatened in the wild.

Photo courtesy of Acro Al, ©2018, All Rights Reserved.


Reef2Reef wishes Acro Al continued success with his giant clams, and we thank him for talking to us and allowing us to use many of his photos.

So, apparently, if you want to sacrifice your whole house and yard, work 24 hours per day seven days per week, and live near the ocean, you, too, can breed Tridacna clams. Good luck with that.

Note from the Editor:

While preparing this article and discussing it with my husband, his first question was, "Can you eat them?" I had to look it up, but the answer is yes, it seems that you can, and the giant clams are considered a delicacy in Southeast Asia and France among other locales. Seems kind of sad, though, to take a 75-year-old clam from the ocean to eat it.



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Author Profile: Cynthia White

Cynthia received her BA in English from NYU. She has been a freelance writer and editor for over 20 years. Now she is a writer and editor on staff at R2R, where her forum nickname is Seawitch.

For 15 years, she kept a dozen freshwater tanks, bred cichlids--Cyphotilapia frontosa--and sold them to pet stores in Calgary. Finally, after years of study, she has come to saltwater side. She lives in British Columbia, Canada, with her husband and three special-needs dogs, a five-minute walk from the Georgia Strait, the Pacific Ocean between Vancouver Island and mainland British Columbia, where the water temperature ranges from about eight degrees C (46F) in the winter to 15 degrees C (60F) in the summer. Bring your dry suit. And some hot coffee.