Corals can live separately but more often they form reefs. Coral reefs take up a tiny fraction of the ocean's bottom but are responsible for a wide diversity of fishes. Researches show that the amount of live coral cover produces significant changes in species richness and abundance of fishes. Many fishes use corals to hide from predators, procreate, feed. It is estimated that corals support 25% of all marine creatures so extinction of corals can lead to horrendous consequences.

The biggest threat to corals is coral bleaching. Bleaching is a stress reaction which causes the pigmented symbiotic microalgae to be expelled, leaving the animals' tissue white or pale. The coral reef becomes uninhabitable. 

The main cause of stress for corals is the warming of ocean water. Other factors include ocean acidification, pollution, overfishing and destructive fishing.

The first mass bleaching event caused by thermal anomalies was recorded in 1998. The sea surface temperatures throughout the tropical Pacific, Indian and Atalantic Oceans dramatically increased which destroyed 16% of coral reefs around the world. In the Indian Ocean around 46% of coral cover was destroyed. Since then, 4 more mass bleaching events took place with 3 of them happening in the past 5 years.

Corals are an important part of the ocean; they form irreplaceable ecosystems that a great number of fishes rely on. Mass bleaching events are becoming more and more frequent so we must keep the temperature rise below 1.5C otherwise we can lose some of the most beautiful places that the ocean has to offer.