The relationship of the triggerfish and other fish is

an example of

Commensalism

Explanation:

Commensalism is a type of feeding relationship that exists between two different organisms where neither organism gains nor loses.

The triggerfish feeds on organisms found under corals which includes shrimps and other smaller organisms etc found in these coral reefs environment.

Its absence has been discovered to have an influence on the population of other species of fish in that environment. They are not harmed neither do they benefit from the other population of fish. Thus the relationship is tagged commensalism.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link:

the answer is :