Hawkfish are species of saltwater fish closely related to the lionfish. They are characterized by their large heads and somewhat elongated, thick bodies. Most species come in vibrant colorations and this, along with their hardy nature and ease of adapting to life in captivity, have made them a popular choice among most marine aquarists. Hawkfish are a vibrantly colored species of fish and comes in shades of red, yellow, orange, brown and black.