Bivalves (Clams) and fishes

Dear All,

Stephen and others have been asking about freshwater bivalves. The
freshwater 'true' mussel (Dreissensia, or zebra mussel) does not have
parasitic larvae at all. The larvae are free-living.

The other 'swan mussel' types, such as Anodonta and Unio, are selective in
who bears the glochidia (the parasitic larvae). Anodonta and Unio use
cyprinoids (i.e. carps); Lampsislis use bass (Huro) and garpike; and
Hemistema uses the salamnder Necturus ("mud puppy").

The larvae settles on the gills or on fins. They cause a swelling (cyst)
and the larvae acquires nutrients from the host. After the tissues of the
cyst are dead, the larvae falls way and settles as a regular clam.

All of this assumes you have at least two specimens. Freshwater bivalves
may be hermaphrodite, but they are not self-fertilizing. So one clam would
be harmless. And a powerful filter would make fertilization of the clams
unlikely, since the sperm would be sucked up.

All these bivalves are naturally long lived (tens of years). They need to
be fed invertebrate food, as with marine bivalves. Otherwise they slowly
starve and die in a few months.

Of course, if you wanted to breed bitterling (Rhodeus) you would need to
keep some clams anyway.




From  Neale Monks' Macintosh PowerBook, at...

Department of Palaeontology, Natural History Museum, London, SW7 5BD
Internet: N.Monks at nhm_ac.uk, Telephone: 0171-938-9007