1. Cody Gramlin
0028526174
FNR 20100
Behavior and Ecology of Chaetodontidae
The family Chaetodontidae, also known as the butterflyfishes, consists of 129
species from 12 genera (Nelson 2016). Butterflyfishes can be found in areas such as
the Red Sea, Eastern Pacific, Western Atlantic, and most concentrated in the Indo-
Pacific regions especially between southern Japan and the Great Barrier Reef (Findley
and Findley 1985). They are generally small-bodied, ranging from 12 to 22 centimeters,
and contain a rich mixture of contrasting white, yellow, orange, and black colors (Nelson
2016). Butterflyfishes generally live in temperate or tropical regions on or near coral
reefs. They reach sexual maturity generally around 90-100mm of length or about one
year of age. Spawning seasons occur between the winter and spring months for many
species in the family (Ralston 1981). They tend to have a primarily corallivorous diet,
preferring stony and soft corals alike, as well as other small, benthic invertebrates and
algae (Roberts and Ormond 1992; Ralston 1981; Findley and Findley 1985). As of
1994, chaetodontids were listed as a vulnerable family to the possibility of extinction
(Nelson 2016). Important topics to discuss aside from the general characteristics that
define the majority of butterflyfishes include their unique pairing habits and territoriality.
Most butterflyfish species are monogamous species, where a single female will
mate with a single male for its entire life and breed through external fertilization. Despite
this, butterflyfishes show no parental care of eggs or larvae. This results in planktonic

2. larvae which aid in the distribution and settlement of new areas. This contradicts the
high parental care typically associated with monogamy (Driscoll and Driscoll 1988). This
implies that monogamy among butterflyfishes may have evolved for reasons other than
parental care (Fricke 1986; Roberts and Ormond 1992). Pairs of butterflyfishes rely
greatly on the bond between themselves and their mates and generally stay within a
close proximity to them. More often than not, these pairs not only retain a close
distance, but remain within each other’s line of sight while grazing in their territory as
well (Tricas 1989; Roberts and Ormond 1992). Many of the bonds formed between pairs
of butterflyfishes can be quite long-term. In a study conducted off the coast of Hawaii by
Driscoll and Driscoll (1988), the greater percentage of pairs observed (Chaetodon
multicinctus, C. quadrimaculatus and C. ornatissimus) remained together throughout
their seven-month study. Upon returning to the site a year later, individuals from five of
the eight original pairs of C. ornatissimus were easily recognizable as well as five of the
six original pairs of C. quadrimaculatus. All could be found in the same territorial bounds
as the prior year. Other experts from similar studies have found the same pairs
observed even three or more years later, highlighting the strength these mating bonds
can truly hold (Roberts and Ormond 1992; Fricke 1986; Driscoll and Driscoll 1988;
Hourigan 1989).
Territoriality displayed among these fish is typically intraspecific, with little to no
interspecific territoriality (Driscoll and Driscoll 1988). Mature adults retain well-defined
territorial boundaries and are aware of other pairs’ territory locations. Large areas of
reefs are subdivided into multiple territories which newer mates are quick to learn
(Righton and Mills 2007; Tricas 1989). Generally, these territorial boundaries are even

3. shaped well enough to construct a detailed map of local chaetodontid territories.
Though pairs generally patrol their territory borders, a mutual understanding of
ownership exists among separate pairs and few aggressive interactions occur (Driscoll
and Driscoll 1988; Fricke 1986). Most territorial interactions were observed from pairs
defending against young, single invaders, or small aggregates of the same species. The
aggression shown consists primarily of chasing activity and rarely lasts more than a
short moment (Tricas 1989). An important characteristic to note is that butterflyfishes
are also known to only show aggression to those of the same gender (Fricke 1986;
Hourigan 1988).
Butterflyfishes retain unique social structures regarding territory boarders and
location. Though the majority of experts are in agreement with the conclusion that
butterflyfishes can indeed be considered territorial, most literature on butterflyfishes
dates back to the 1980’s and 1990’s. Many questions are still left unanswered or up for
debate. For instance, much is still unknown about niche partitioning or how different
coral resources are used among chaetodontid species. For another example, why do
some experts believe that chaetodontids are entirely non-territorial while others have
recorded actual observations of this occurring? Is this discrepancy a result of human
error, related to location, or maybe another lurking variable? With this in mind, it may be
time to conduct more research to follow up on the current knowledge of this socially
complex family of fishes.
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4. Literature Cited
Driscoll, J.W., and J.L. Driscoll. 1988. Pair behavior and spacing in butterflyfishes
(Chaetodontidae). Environmental Biology of Fishes 22(1): 29-37.
Findley, J.S., and M.T. Findley. 1985. A search for pattern in butterflyfish
communities. The American Naturalist 126(6): 800-816.
Fricke, H.W. 1986. Pair swimming and mutual partner guarding in monogamous
butterflyfish (Pisces, Chaetodontidae): a joint advertisement for territory. Ethology 73(4):
307-333.
Hourigan, T.F. 1988. Environmental determinants of butterflyfish social systems.
Environmental Biology of Fishes 25(1): 61-78.
Irons, D.K. 1989. Temporal and areal feeding behavior of the butterflyfish,
Chaetodon trifascialis, at Johnston Atoll. Environmental Biology of Fishes 9: 187-194.
Nelson, J.S. 2016. Family Chaetodontidae – Butterflyfishes. Retrieved from
FishBase.
Ralston S. 1981. Aspects of the reproductive biology and feeding ecology of
Chaetodon miliaris, a Hawaiian endemic butterflyfish. Environmental Biology of Fishes
6(2): 167-176.
Righton, D., and C. Mills. 2007. Application of GIS to investigate the use of space
in coral reef fish: a comparison of territorial behaviour in two Red Sea butterflyfishes.
International Journal of Geographical Information Science 20(2): 215-232.

5. Roberts, C.M., and R.F.G. Ormond. 1992. Butterflyfish social behaviuor, with
special reference to the incidence of territoriality: a review. Environmental Biology of
Fishes 34(1): 79-93.
Tricas, T.C. 1989. Determinants of feeding territory size in the corallivorous
butterflyfish, Chaetodon multicintus. Animal Behaviour 37(5): 830-841.
Yabuta, S. 2002. Uncertainty in partner recognition and tail-up display in a
monogamous butterflyfish. Animal Behaviour 63(1): 165-173.
Yabuta, S. 1997. Spawning migrations in the monogamous butterflyfish,
Chaetodon trifasciatus. Ichthyological Research 44(2): 177-182.
Zekeria, Z.A., Y. Dawit, S. Ghebremedhin, M. Naser, and J.J. Videler. 2002.
Resource partitioning among four butterflyfish species in the Red Sea. Marine &
Freshwater Research 53(2): 63-68.