Lice and worms are common goldfish tank parasites, both of which can potentially lead to health problems in your fish and so, should be dealt with as soon as a potential issue arises.
What are goldfish lice and worms?
Fish tank lice and worms are parasites that rely upon goldfish to thrive and reproduce, and will often be most prevalent in overcrowded tanks and on fish that have recently been bought from a pet store.
It is of course important to ensure that you do not let your tank become overcrowded, and that you quarantine any new fish for 14 days to a month before you introduce them to your main tank.
Tapeworms, anchor worms and body lice are three of the most common parasitic problems that can affect goldfish, and these three invaders are sometimes found together.