Cambridge Secondary (7-9). Stage 7. MCE Science. Workbook - Unit 4: Classifying Living Things - Question 37

Tropical fish are popular for home aquariums. An example is the clownfish, which is also called the anemone fish. Some species of tropical fish live in coral reefs. Coral reefs are made of small, simple animals that attach themselves to one another. Corals need warm water, but not too warm.

Scientists found that some species of tropical fish in the oceans are decreasing in number. Suggest a reason using evidence from the text above.