On 10 Oct 1995, Martha Lanclos wrote:
> Can anyone tell me, via e-mail is okay, of particular ectoparasites on
> goldfish, quite possibly with common name "anchor worms"?
"Anchor worms" are copepod ectoparasites of cyprinids, and sometimes
salmonids and other fish. The holdfast organ for these copepods is
buried in the host tissue, as is the mouth, and part of the trunk. Only
one host is required for completion of the life cycle that involves free living
naupliar stages, and copepodid stages that are usually found on the
gills. Because of their size, they can be lethal to goldfish as adults,
and large numbers of copepodids on the gills can also cause trouble.
The embedded adult females are difficult to kill, so treatment ususally
focuses on the larval stage which requires several weeks of treatment.
Usually an organophosphate insecticide is used every 7 days, as the
copepodid development takes 8-9 days (@27C), to prevent reinfection until
the female dies. Sodium chlorite is less toxic, and has been shown to be
effective, but does kill off bacterial filters (although resistant bacteria
will recolonize). You may want to remove the worm by hand, and switch the
fish to a seperate tank for a week, as the remaining copepodids will die
without a host in about 6 days, and you won't have to mess with any
chemicals. - Derek Zelmer