Coral reefs provide homes and nursery grounds to many fish species. In fact, about one-third of all saltwater fish species live at least part of their lives on coral reefs. That’s at least 5,000 different species of wildlife! This is especially amazing when you consider that coral reef habitat makes up less than one percent of our oceans.
The diversity of fish found on reefs is overwhelming. These range from large predators – like sharks, grouper, and barracuda – that prey on other fish, to small and colorful fish – like clownfish or mandarinfish – that eat plankton. Along with their respective roles in the marine food web, many of these fish serve other important roles in our oceans. For example, herbivores like surgeonfish and parrotfish keep seaweed-like algae from taking over coral reefs. Cleaning wrasse help keep larger fish healthy by removing parasites and dead skin – sometimes from inside the larger fish’s mouth! In addition to their ecological value in the oceans, more than one billion people around the world rely on reef fish as a source of food and income.
Despite their importance, coral reef fish are not always managed in a sustainable way. Fishermen can sometimes rely too heavily on certain species, causing some reef fish to be severely overharvested, which can have negative consequences for reefs across the world. Depletion of parrotfish and surgeonfish populations allows algae to grow unchecked, causing some coral reef ecosystems to morph from a beautiful seascape of corals to fields of rubble and seaweed. Some fishermen have even used dynamite to kill and capture fish, which destroys the reef framework itself.
Reef fish are also collected to serve as aquarium pets or even decorative items. More than 1,800 species of reef fish, 140 species of corals and 500 species of other invertebrates are used by the pet, curio and home décor trades. Although trade can be conducted sustainably, wildlife populations are often overexploited to feed the demand for these animals. For instance, populations of Banggai cardinalfish, clownfish, and mandarinfish have been overexploited by heavy collection for the aquarium trade. This can lead to local extinctions, disrupted mating systems, and fewer fish on the reef. In other cases, it is not the number of fish collected but the way in which they are taken that poses the biggest threat. Some collectors for the pet and food trades dump poisons like cyanide into the water to stun fish and make them easier to capture. Though some of the target fish survive and are collected, the cyanide kills many fish, corals and reef wildlife, and degrades the reef habitat itself.
The good news is that many of these threats are problems that we can address, and Defenders is working to improve the conservation and management of coral reefs. By working with industry leaders to put a stop to harmful collection practices and ensure sustainable methods are being used, we can make great strides towards protecting coral reefs and reef fish from this unnecessary threat.