I took this from this website: http://www3.sympatico.ca/drosera1/fish/worms.htm
Ostracods (seed shrimp, clam shrimp)
Control - Complete eradication is often unsuccessful, except for larger species, which seem more fragile. Regular aquarium maintenance and proper filtration usually keep the populations down to unapparent levels.
Because of their structure, Ostracods are extremely resilient against toxins. By closing the two shells, they can survive extended amounts of time in the presence of medications and pesticides. Even if they die, the shells serve to protect the unborn young until conditions are right again.
Notes - Ostracods are called seed shrimp or clam shrimp, and with good reason. The creatures exist inside opposing shells that look and function just like those of clams. Dead Ostracods are often wrongly identified as clams.
In most species, no males have ever been observed. Reproduction is by parthenogenesis, the production of clonal young. Many species also experience a yearly diapause. The adults die when their habitat dries up, or winter approaches. The young are safely harbored within the body of the parent, and emerge the following spring or rainy season.
Ostracods could only become a problem if they extremely over populate a tank, a condition the author has never seen in a fish aquarium. Only in infusoria jars does this seem to occur.
Because of their hard carapace, Ostracods are usually unappreciated as fish food. Their use as such is not recommended.