<span>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!</span>
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! :)
The answer in the space provided is anaerobic respiration.
It is because this allows of having to utilize other substance than oxygen such
as nitrate or sulfate to be their electron acceptors in which is for organisms
that undergoes respiration.
