''Elassoma evergladei'', or the Everglades pygmy sunfish, is a species of fish from the genus ''

Elassoma ''Elassoma'' is a genus of freshwater fish, the only member of subfamily Elassomatinae of the sunfish family Centrarchidae in the order Perciformes. It is sometimes classified as a separate family, the Elassomatidae, in a monotypic suborder, ...

'' (the pygmy sunfishes) that is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to North America.

Description

The fish can grow to a maximum length of 3.4 cm (in

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

), and it generally grows to 2.3 cm (TL). Scales are present at the top of its head. Its mouth is both small and oblique. The fish does not have a lateral line. A crescent-shaped area behind each eye may be gold or iridescent blue. It has dark lips. Egg count in the ovaries of females in captivity ranged from 115 to 500, increasing with the fish's size. The fish has variable color and form. Its body is generally colored brown with darker spots. The fish has several rows of dark red spots on its dorsal and anal fins. "Nonbreeding" fish may have light streaks, mottling, or blotches. Females of the species in general are colored brown on their backs with mottled brown and cream/white coloring underneath, or they may be reddish brown. The females have no markings. "Breeding" males are colored black with iridescent blue spots. Males have black fins with or without brown spots. Male bodies may be black, brown, or dark green with blotches or spots. A few indistinct dark bars may be present on the male body. Males may have brassy or blue-green iridescent scales scattered across their bodies. According to one source, males are dark black and have

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

blue flecks, and females have a brown coloration.

Distribution and habitat

The Everyglades pygmy sunfish can be found in the United States from the end of

Cape Fear River The Cape Fear River is a long blackwater river in east central North Carolina. It flows into the Atlantic Ocean near Cape Fear, from which it takes its name. The river is formed at the confluence of the Haw River and the Deep River (North Carol ...

, North Carolina to Mobile Bay, Alabama. It may also be found from the south of Florida to the northern end of the

Everglades The Everglades is a natural region of tropical climate, tropical wetlands in the southern portion of the U.S. state of Florida, comprising the southern half of a large drainage basin within the Neotropical realm. The system begins near Orland ...

. The fish has been found more often in the natural marshes rather than the constructed marshes of central Florida. The fish lives in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

and

demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

habitats at a pH range of 7.0 to 7.5 and a temperature range of 10 to 30 degrees Celsius. They reside in

swamps A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

, sphagnum bogs,

sloughs A slough ( or ) is a wetland, usually a swamp or shallow lake, often a backwater to a larger body of water. Water tends to be stagnant or may flow slowly on a seasonal basis. In North America, "slough" may refer to a side-channel from or feedi ...

with heavy vegetation, canals, overflow pools, ponds, lakes, and streams; generally over

mud A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

, sand, limestone, or

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

. They exist in such areas where the current is slow and water levels fluctuate. They prefer shallow areas as well as areas of vegetation. The species tends to stay restricted to black water environments more than other species of the genus. The species' population density is highly dependent on environmental conditions. However, the fish is considered common in most of its range and its overall population (estimated at 100,000 as of 2013) is large and stable.

Behavior

The Everglades pygmy sunfish tends to live alone. As an

invertivore Feeding is the process by which organisms, typically animals, obtain food. Terminology often uses either the suffixes -vore, -vory, or -vorous from Latin ''vorare'', meaning "to devour", or -phage, -phagy, or -phagous from Greek φαγε ...

, the fish preys on worms and other crustaceans in its habitat. Prey include cladocerans, dipteran larvae, annelids, chironomids, copepods, ostracods, and newly hatched snails. Where food is centrally located, males will establish territories with closer proximity to the center based on dominance. In environments of evenly distributed food, males will range freely and will not establish territories. Like many other fish species, ''Elassoma evergladei'' is

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...

. A female may lay 40 to 60 eggs, and a male will guard the eggs. Eggs are laid in

aquatic plants Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

, especially in those from the genus '' Ceratophyllum''.

In captivity

In captivity, males will establish their territory in feeding areas.

Human significance

The fish is sold commercially for

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

s. One author considers it "the best-known member of the group ygmy sunfishesin the aquarium hobby." In 2013, the IUCN Red List of Threatened Species named the species Least Concern because of its "large extent of occurrence, large number of subpopulations, large population size, apparently stable trend, and lack of major threats."

Etymology, taxonomy, and history

''Elassoma'' refers to the Greek words ''elasson'', for "smaller", and ''soma'', for "body". ''Evergladei'' means "of the Everglades", named for the location the

type specimens In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes t ...

were captured.

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Univer ...

first described the species in 1884, and his original specimens measured one inch in length. One 1918 publication mentioned the species' common name as the "southern pygmy sunfish".