The azure damselfish (Chrysiptera hemicyanea) is a vibrant, two-toned marine fish known for its bright electric blue front half and yellow posterior portion and tail. It is a popular and hardy choice for saltwater aquariums. 

Native to the eastern Indian Ocean and Western Pacific, the azure damselfish typically inhabits lagoons and near-shore coral reefs, particularly among branching corals like Acropora. They are diurnal, active during the day, and use the coral structures for protection and a sense of territory. 

In an aquarium setting, they are known for their territorial behavior and should be provided with plenty of live rock formations to create hiding spots and help establish boundaries. While they can be housed with other semi-aggressive fish, caution is advised when housing with very passive species or multiple damselfish in smaller tanks. 

The azure damselfish is an omnivore. In the wild, their diet primarily consists of plankton, copepods, and some algae. In captivity, they are not picky eaters and will accept a varied diet, including: 

Feeding small meals two to three times a day is a good practice to ensure they receive adequate nutrition. 

Due to their hardiness and ability to tolerate minor changes in water chemistry, the azure damselfish is recommended for beginner hobbyists. A minimum tank size of 15-20 gallons is suggested for a single fish, and a 30-gallon tank or larger for a pair or small group to minimize aggression.