Lepomis cyanellus

Alternative Names

 * Green Sunfish

Sexing

 * Males are slightly larger than females of the same age.

Tank compatibility

 * The Green Sunfish (Lepomis cyanellus) is an aggressive centrarchid, and although smaller than its cousins the Bluegill (Lepomis macrochirus) and the Pumpkinseed (Lepomis gibbosus), it can dominate them behaviourally. In the wild, green sunfish inhabit the weeded littoral zone, excluding Bluegill and Pumpkinseed. In captivity, the green sunfish is a powerful fish, capable of overpowering many other species, even fish larger than itself. This species may be stocked in species tanks, where they form loose schools in which no one is hyperdominant, although breeding behaviour may necessitate removing some individuals. Green sunfish may also be kept with similarly sized catfish, such as the Brown Bullhead (Ameiurus nebulosus). It is not advisable to house green sunfish with other Sunfish, because the green sunfish are likely to injure the less aggressive species. It is possible to keep Green Sunfish with Neotropical Cichlids of similar size and temperament, such as the Convict Cichlid (Archocentrus nigrofasciatus), Texas cichlid (Herichthys cyanoguttatus), or Jack Dempsey (Cichlasoma octofasciatum). However, given the subtle differences in their behavioural repertoires, it is more prudent not to mix them.

Diet

 * Green Sunfish are the most predatory species of the genus Lepomis, preying on insects, crustaceans, and smaller fish. In captivity, however, they easily adapt to thawed frozen items, such as brine shrimp or blood worms, and pelleted foods marketed for Cichlids. They can also be given live foods like earthworms or "feeder" fish, but this is not necessary.

Feeding regime

 * Once or twice a day for adults, four to six times a day for fry (babies).

Environmental specifics

 * Green sunfish come from the quiet, cool to warm waters of North America's Midwest, but have been introduced elsewhere. They prefer thickly vegetated, slow-moving water near the edges of ponds or lakes where they can stalk smaller fish, and feel secure from larger predators, such as Largemouth Bass (Micropterus salmoides) or wading birds. Their aggressive behaviour allows them to occupy this favoured habitat to the exclusion of other fishes. Green sunfish can also be found in the deeper, calmer parts of streams and creeks, or schooling in open water when food is available and it is safe to do so. In the aquarium, they should have ample plant cover, as well as open areas for free swimming. The gravel should be dark to tan in colour, and of fine grain in the event that the male Green Sunfish attempts to excavate a spawning pit or nest with his caudal fin (unlike Cichlids, which use their mouths to dig).

Behaviour

 * Like other perciform fish (Cichlids, anabantoids), Green Sunfish appear to make themselves look larger during agonistic bouts with rivals. To intimidate another fish from the side, green sunfish extend their fins and wave their tail in their opponent's face. To look more intimidating from the front, Green Sunfish expand or flare their gill covers (opercula). If these tactics don't work, actual fighting with bodily contact may take place, in which the green sunfish will bite the other fish. Green Sunfish are considered a good "wet pet", though, because they interact with people through their aquarium glass, appearing to get excited at feeding times.

Breeding

 * In order to spawn, Green Sunfish require a winter cooling period below for one to four months, followed by a warmer period of . The male will then make a nest, which he excavates with swishing motions of the caudal fin. This is why it is important to have gravel that is not too course; it can discourage the male from excavating if it is too difficult to move. Once his nest is prepared, he will court one or more females to it with display behaviour, which resembles agonistic (fighting) behaviour, except it is slower and does not involve biting. During courtship and spawning, both sexes exhibit bold, dark green vertical bands on their flanks. Spawning takes place with the male and female pressing their vents close together. After the eggs have been laid and fertilized, the male will drive of the female(s), which do not take part in rearing the young. Once there are eggs or baby fish in the aquarium, turn off the main undergravel, canister, power, or trickle filter, and switch to a sponge filter instead, which creates the gentler circulation that fry need.


 * The fry take about three days to absorb the yolk sac and become free-swimming. It will then take an additional three days for them to become mobile enough to leave the male's nest, and the male will make no attempt to gather them back together again. At this time, the male's job is done, and he will no longer protect the babies, so in captivity, they must be separated. Sunfish fry can be raised in much the same way as Cichlid fry, and can be fed brine shrimp nauplii, or boiled egg yolk (ground in water to a fine paste) for the first two weeks of life. They can also be fed infusoria, which is a generic term for microscopic aquatic organisms. Infusoria can be cultured in advance by taking a sample of aquarium water in a jar, and placing the jar on a window sill or shelf that receives plenty of sunlight. After a few days to a week, the water will appear cloudy, due to the many harmless micro-organisms growing there. To feed the baby fish, simply harvest a few millilitres of infusorial water at a time and place in the aquarium near the babies. Whatever form of baby fish food you use, feed them four to six times a day for the first two weeks. After that, they can be fed finely powdered flake food for an additional month. Then, as they become more active and their mouths get larger, they can be given the same items as adults (see "Diet" and "Feeding regime" above), only in smaller quantities.


 * There are some similarities between the breeding of centrarchids and Cichlids, in that both families exhibit complex courtship and rearing behaviour. However, there are important differences in pair-bonding between the adults, and in the defence of the young that aquarists should be aware of as well.

Identification

 * True to their name, Green Sunfish have a yellowish-green base colour all over their body. They have iridescent, wavy blue lines on their cheeks, as well as iridescent blue flecks on their flanks. Their pectoral fins are a clear to faint yellow colour, their pelvic fins white to yellow, and their belly a pale yellow. Their unpaired fins have clear to white, yellow, or orange edges along the edges. As in other Sunfish, there is a black "ear flap" where the operculum meets the head. When excited or breeding, ten to twelve dark green to black vertical bars appear on the head, flanks, and caudal peduncle (base of the caudal fin, or tail). The most visible bar connects the single black spots found at the base of the dorsal and anal fins. Given adequate room and nutrition, green sunfish may reach standard length, but commonly reach about  standard length.

Species note

 * Green Sunfish are a sport fish in North America, so obtain a fishing license prior to collection. Green Sunfish may be captured using conventional hook-and-line angling, but this may injure their mouths. Thus, baiting a minnow trap is a safer way to catch smaller fish, and using a net is a safer way to catch larger individuals.