Introduction

The bicolor damselfish (scientific name: Stegastes partitus) is a member of the damselfish family (Family Pomacentridae) that lives on coral reefs in the western Atlantic and the Caribbean Sea  It is one of the five most abundant fish species in this region.

Bicolor damselfish. Source: ''Reef Fish Identification'', New World Publications © 1994.

Scientific Classification Kingdom: Animalia (Animals) Phylum:--- Chordata Class:------ Osteichthyes (Bony Fishes) Order:-------- Perciformes Family:-------- Pomacentridaedae (Damselfishes) Genus:----------Stegastes Species:--------- Stegastes partitus (Poey, 1868)

Physical Description

Adult bicolor damselfish are small, ranging from five to ten centimeters in length. They their name from their typical coloration: the front portion of their body is black while the back portion of their body is white. In some geographic locations, the ventral portion of the front of the fish is yellow instead of black.

Distribution

They are found in the Western Atlantic including southern Florida (USA), Bahamas, and the Caribbean Sea, and may extend as far south as Brazil.

Habitat

They typically live on coral reefs at depths ranging zero to 100 meters.

Feeding Behavior

Bicolor damselfish are plantonivores that feed on copepods, pelagic tuncates, and larvae in the water column above the reef. The distance that foragers stray from the reef depends on size; larger individuals may forage over 1.5 meters from the reef while smaller individuals remain close to the reef for protection,

Behavior

Bicolor damselfish form territories on the reef and form large colonies that contain all sizes, and both sexes of fish.  Dominance hierarchies in these colonize are determined by size, with larger individuals dominating smaller individuals in a series of fights and challenges.  Thus, larger individuals tend to inhabit larger territories than smaller individuals. Individuals communicate by body position and posture, color patterns (they are capable of rapidly changing their colors), as well as vocalizations during aggresive interactions.

Reproduction

Most reproduction occurs in the warm months, with peak activity occuring in the week following the full moon.  Courting males change color so that their head and tail sections are bright black while their midsection remains white.  Males build nests, hidden from view in small holes or shells, and attempt to attract females by performing a series of dips and tillts towards the females and by emitting a series of chirps. Females are able to identify individual males by these calls and can also determine the size of the male.  In general, males that perform the mosts dips and tilts attract the most females.   Spawning typically occurs in the morning and females may lay between 500 to 5000 eggs in a nest (depending on the size of the female).  In general, only one female lays eggs in each nest, although about one third of the nests contain eggs from multiple females.  Males defend the eggs from potential egg predators until the eggs hatch abpout three and a half days later. The pelagic jeuvenile stage lasts from  27 to 31 days before the larvae settle on the reef. Both sexes reach maturity in about one year and may survive for three to four years.

Conservation Status

Bicolor damselfish are widespread and abundant throughout their distribution, so that the species is not deemed to be at risk.

References and Further Reading

• Encyclopedia of Life. Species curator: C.Michael Hogan. 2011. Stegastes partitus (Poey, 1868)
• Fishbase. Stegastes partitus : Bicolor damselfish
• P.Humann and N.Deloach (Editors) 1994. Reef Fish Identification: Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. ISBN: 1878348078
• N.Deloach. 1999. Reef Fish Behavior, Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. ISBN: 1878348280