The coral never holds quite the pink i hope for and fish continue to catch strange sickness like the angel fish, greta who has a parasite. what does the word parasite mean

A parasite is an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense. Hope I helped!

A parasite is an organism that survives in a non-mutual relationship by obtaining nutrients from the host organism or lives off the host organism. In the case of parasitism, the host is harmed while the "parasite" receives benefits that could range from nutrients to shelter. This strange sickness the Angelfish is receiving is most likely due to the parasite in this instance deriving nutrients from the organism and depleting it's immune system or a disease passed on by a parasite. Hope this helped! :)