Why do Clams Die in Aquariums?

http://www.ipsf.com Why do Tridacnid clams sometimes die unexpectedly in aquariums? Much of the mortality of giant clams in captivity relates to the size of the byssal gape on the underside of the clam.

The blue clams Tridacna maxima and T. crocea burrow into coral heads and attach tightly to the coral with strong byssal threads. When harvested in the wild, these clams have a large, unprotected byssal gape which can allow an entry point for predators and parasites. Because the byssal threads grow out of the foot of the clam, cutting the byssal threads at harvest may damage the foot. This internal injury will not be outwardly visible but it may lead to declining health and death of the clam weeks or months after its harvest.

The larger, non-blue clams including T. derasa and Hippopus hippopus live unattached on the substrate and have very narrow byssal gapes. They can close their shells tightly to keep out parasites and predators including snails, crabs and some types of dangerous fireworms. Moreover, there is a much lower probability of damage to the foot of these species when they are harvested.

Hippopus hippopus has a thick shell and zipper-like shell margins. It is the most predator- and parasite-resistant of the giant clams in mariculture operations and probably in aquariums as well.

Watch more videos in our giant clam educational series:
http://www.youtube.com/user/GeraldHeslinga#g/u

Read Joseph Rosewater's classic monograph on the family Tridacnidae in the Indo-Pacific:
https://docs.google.com/fileview?id=0BwZ8-4sMhZ0OZWIwMGUzYWItZDY0Ni00ZmVmLWIx...

Read the classic Aquaculture article on Cymatium snail predation on giant clams by Perron, Heslinga and Fagolimul:
https://docs.google.com/fileview?id=0BwZ8-4sMhZ0OMTE0ODAyOWUtZDAxMi00N2FiLWJl...

Learn more about predatory fireworms:
http://www.youtube.com/watch?v=C_KbY2-hV_4

[Videography and narration by Gerald Heslinga of Indo-Pacific Sea Farms (www.ipsf.com). Thanks to Steve Lindsay for 3 Kosrae Tridacna sp. images in the credits segment. Song credit: Mark Knopfler, What it Is. Final photo credit: Mahalo nui loa to Sarah, Tien and Lisa.]

Further reading:

Beckvar, N. 1981. Cultivation, spawning and growth of the giant clams Tridacna gigas, T. derasa and T. squamosa in Palau, Caroline Islands. Aquaculture 24: 21-30.

Fitt, W. K., C. R. Fisher, and R. R. Trench. 1986. Contribution of the symbiotic dinoflagellate Symbiodinium microadriaticum to the nutrition, growth and survival of larval and juvenile tridacnid clams. Aquaculture 55: 5-22.

Fitt, W. K., G. A. Heslinga, and T. C. Watson. 1992. Use of antibiotics in the mariculture of giant clams (F. Tridacnidae). Aquaculture 104: 1-10.

Fitt, W. K., G. A. Heslinga, and T. C. Watson. 1993. Utilization of dissolved inorganic nutrients in growth and mariculture of the tridacnid clam Tridacna derasa. Aquaculture 109: 27-38.

Hastie, L. C., T. C. Watson, T. Isamu and G. A. Heslinga. 1992. Effect of nutrient enrichment on Tridacna derasa seed: dissolved inorganic nitrogen increases growth rate. Aquaculture 106: 41-49. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0OOW...

Heslinga, G. A. 1989. Biology and culture of the giant clam. In: Manzi, J. and M. Castagna (eds.), Clam Mariculture in North America. Elsevier, Amsterdam, 461 p. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0ONj...

Heslinga, G. A. and W. K. Fitt. 1987. The domestication of reef-dwelling clams, BioScience 37: 332-339. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0ONz...

Heslinga, G. A., Perron, F. E. and Orak, O. 1984. Mass culture of giant clams (f. Tridacnidae) in Palau. Aquaculture 39: 197-215. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0OMz...


Heslinga, G. A., Watson, T. C. and T. Isamu. 1990. Giant Clam Farming. Pacific Fisheries Development Foundation (NMFS/NOAA). 179 p. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0OMD...


Maruyama, T. and G. A. Heslinga. 1997. Fecal discharge of zooxanthellae in the giant clam Tridacna derasa, with reference to their in situ growth rate. Marine Biology 127: 473-477. https://docs.google.com/viewer?a=v&pid=explorer&srcid=0BwZ8-4sMhZ0ONW...


Perron, F E., G. A. Heslinga and J. O. Fagolimul. 1985. The gastropod Cymatium muricinum, a predator on juvenile tridacnid clams. Aquaculture 48: 211-221. https://docs.google.com/fileview?id=0BwZ8-4sMhZ0OMTE0ODAyOWUtZDAxMi00N2FiLWJl...

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[bobthercperson]

make more vid

[MadHatterReefs]

Great Video. Very informative.

[DATJACK61]

wow.the first video ive ever seen on youtube that the trolls have not ruined.

[muffemod]

Knowledge

[bilbobag111]

I've been looking forward to a new video from you. Great information! Thanks.

[weareallwet]

sweet

[waynecreech]

Very cool!