Panamic Sergeant Major

Abudefduf troschelii have five dark bands on the lateral surfaces of the body with dorsal yellow spaces in between. These dark bands spread towards the ventral side of the fish creating black stripes. This eye catching coloration of the fish is one of the reasons that they are popular aquarium fishes. Their pectoral fins are lengthened, slender, and paddle-shaped allowing them to swim fast and change direction quickly around coral reefs. This is a common morphology among coral reef living fish. These pectoral fins are structured with a long, straightened hydrodynamic leading edge, and a rounded hydrodynamic trailing edge allowing them to easily maneuver around pieces of rock and coral. Compared to other damselfish, A. troschelii have relatively large eyes, and a long angular shaped head.

Abudefduf troschelii are found widely throughout the Eastern Pacific and are endemic to this area. They are commonly found in Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Peru, and the United States to name a few. In these places, this species is abundant in coralline and sandy bottoms, but they can also be found at rocky bottoms and tide pools where they are usually found in large aggregations. Furthermore, this species can be found in the pelagic area of the neritic feeding on plankton. This neritic area where A. troschelii are commonly found, is made up of massive corals, deep rocky walls, and shallow exposed reef.

These Eastern Pacific damselfish are feeders whose diet consists mainly of plankton in the pelagic zone and mid-water, but they also graze on benthic invertebrates and algae on their coral reef habitat. These feeding tendencies make them an omnivorous species. The physical structure of the A. troschelii mouth is one that it small but conveniently located so that it can easily feed on small plankton suspended in the water column and small bits of algae attached to pieces of benthic structure.

Abudefduf troschelii spawn within nine days on either side of the new moon, and hatching occurs after four days where newborns are hatched during the hour after sunset. Extended periods of spawning can occur during seasonal increases in plankton productivity. This seasonal increase is due to upwelling and leads to an increase in egg production of the species. During a wet season, this reproductive process lasts three to four days. In a dry season, on the other hand, this process can be drawn out to 8 days. Due to this, reproductive patterns are found within A. troschelii populations particularly during wet seasons. Reproductive patters of this species is beneficial because a hatching taking place at dusk results in favorable tides allowing newborns to be transported away from reef-based predators found at the time of a new moon.