Green Sunfish

Quick Take

• This small fish outcompetes and intimidates every native species in habitats where it's been introduced, and its size has nothing to do with that. Invasive range and adaptability →
• Green Sunfish swim in schools for protection yet are fundamentally solitary, and that contradiction is exactly why controlling their populations is so difficult. Schooling yet solitary behavior →
• Their nesting ritual produces a side effect that makes reliably identifying them nearly impossible, and this happens entirely by accident. Cross-breeding and hybrid offspring →
• Before you swim in a lake with a healthy Green Sunfish population, there's something about their behavior you should know first. Biting swimmers explained →

The Green Sunfish is a small freshwater fish that occurs throughout the USA and northern Mexico. American Anglers refer to them as panfish because they are small enough to fry whole.

While the Green Sunfish is small, it is highly aggressive and predatory. They have stocky bodies and big mouths. Their closest relative is the bass, more so than any other species of Sunfish.

Anglers love them because of their feisty nature, and they are usually caught alongside other species of panfish like the Redear Sunfish and Bluegill.

Three Amazing Green Sunfish Facts

• Green Sunfish are considered an invasive species in Florida and New Jersey, and anglers are often encouraged to remove them when caught to help control their populations. Regulations regarding possession may vary by state.
• Green Sunfish are biters, so don’t go swimming in areas where their populations are high.
• People do eat Green Sunfish; however, they are not generally recommended for consumption, specifically for children, because they are bony.

Classification and Scientific Name

The Green Sunfish’s scientific name is Lepomis cyanellus and they are members of the order Perciformes. This order comprises over 10,000 species in 1,500 genera and 160 families, making them the most abundant family of vertebrates in the ocean. In many freshwater habitats, they are also the most dominant.

Green Sunfish belong to the family Centrarchidae, and the 29 species that belong to this family only occur in North America. The majority of Sunfish species build a nest for their eggs, and the males protect the nest. They inhabit large lakes and are apex predators in their habitats. However, they are hunted as sport fish.

Appearance

The Green Sunfish is a stocky fish with a big mouth and an upper jaw protruding to the middle of the eye. Their back and sides are a blueish-green color that fades into a pale white or yellow on the belly. In addition, vertical, black lines are sometimes evident on their sides.

The sides of their heads are covered in blue mottlings and streaks, and breeding males’ pelvic fins are pink or white. In addition, their tails, anal fins, and dorsal fins have a white or salmon-pink tip.

Green Sunfish’s backs and dorsal fins have a dark patch, and their pectoral fins are rounded. Lastly, these aggressive predators have a long, dark ear flap.

They are a bit bigger than other Sunfish, can grow up to 12 inches long, and weigh around 2.1 pounds.

Behavior

Most small fish species live in packs or schools, as does the Green Sunfish. This benefits them because it provides protection from predators and is considered a life-saving mechanism.

Green Sunfish often cross-breed, making it difficult to identify them correctly, and they are often mistaken for their cousins, the bluegill. Additionally, they tend to overpopulate, which hinders their growth. This is because when there is less space in a habitat, the less an animal grows.

These small fish are highly aggressive. Once they have established dominance over a particular habitat, they waste no time attacking and intimidating the other small fish that live there.

Generally, Green Sunfish outcompete any native species in areas where they have been introduced. While they swim in schools for safety, they are mainly solitary and don’t communicate with members of the same species. In addition, they are fiercely protective of their nests and will exert physical force if anything comes too close.

Habitat

The Green Sunfish is native to central North America. They are distributed from the eastern plains of the Rocky Mountains to west of the Appalachian Mountains, which include the northeastern regions of Mexico and southeastern lakes in Canada.

However, they were also introduced to most of the USA, except for Florida and several northeastern States. In addition, they were introduced as an exotic species in:

• Africa
• South America
• Asia
• Europe

They are highly adaptable and can thrive in various aquatic conditions, which is why their numbers increase yearly. Green Sunfish prefer smaller habitats with weak currents, like streams and ponds. However, they can acclimate to both turbid and clear water and sometimes inhabit weedy lake shorelines and lazy rivers.

Diet

Green Sunfish prefer live food but are omnivores and eat plant matter as well. The best bait to catch them with is:

• Bloodworms
• Aquatic insects
• Waxworms
• Mealworms

However, they prey on animals like crayfish, smaller fish, fish eggs, zooplankton, invertebrates, and snails as well.

Predators and Threats

Juvenile Green Sunfish are less colorful than their parents because they need to blend in with their surroundings to avoid predators. However, sometimes, their camouflage does not work and they fall prey to predators such as the:

• Largemouth Bass (Micropterus salmoides)
• Channel catfish (Ictalurus punctatus)
• Flathead catfish (Pylodictis olivaris)
• Bullhead catfish (Ameiurus spp.)

Green Sunfish are listed as Least Concern on the IUCN Redlist, reflecting their wide distribution and stable population.

Reproduction, Babies, and Lifespan

These feisty fish begin spawning during the warmer months; however, the exact time varies depending on location and water temperature. The males build nests in shallow water, usually near a type of shelter like submerged logs or rocks.

Green Sunfish males will defend the nest from other males by using visual displays and physical force if necessary. They generally court females with grunts that entice them into the nests; however, just building the nest sometimes attracts a female.

But the courtship does not stop there. The pair will dance, swimming with each other until the female swims up to the nest to deposit her eggs. Females lay between 2,000 and 26,000 eggs and leave. The males will stay with the eggs until they hatch, which takes around 3 to 5 days. In addition to standing guard, the males fan the eggs with their fins, which keeps them clean and oxygenated.

Once the eggs hatch, the fry stay close to the nest for several days but eventually leave for good in search of food. Once the fry have left the nest, males will try to entice another female to lay eggs in their nest.

Green Sunfish generally build nests in areas near members of the same species, as well as other Sunfish. Because the nests are so close together, females can deposit some of their eggs into a different species’ nest, which is cross-breeding; as a result, the next generation will contain hybrids. These fry grow into juveniles that resemble a combination of both parents, making it almost impossible to distinguish one species from another.

Lifespan/Longevity

The Green Sunfish’s lifespan in the wild is between 4 and 6 years, and in captivity, they have an average lifespan of 7.5 years.

Population

There are 13 species of true Sunfish in the world, and most of them occur in various areas of North America, making it difficult to estimate their total population size. However, their numbers keep increasing each year.