If a fish were put into cup of coffee what would happen?

If you were to put a fish into a cup of coffee, it would likely die very quickly. Coffee contains a number of chemicals that are harmful to fish, including caffeine, tannins and chlorogenic acid. Caffeine can cause the fish's heart to race and its blood vessels to constrict, which can lead to death. Tannins can damage the fish's cells and tissues, leading to organ failure. Chlorogenic acid is a powerful antioxidant that can disrupt the fish's natural defenses and make it more susceptible to disease.

In addition to these chemicals, coffee also has a low pH level, which can be harmful to many types of fish. Fish prefer water with a pH level of around 7, but coffee can have a pH level as low as 4.5. This acidic water can damage the fish's gills and skin, and make it difficult for them to breathe.

Overall, putting a fish into a cup of coffee is a dangerous and potentially fatal thing to do. If you want to keep fish, please use a proper aquarium with the correct water quality and environment.