Damselfish Aggression

Influenced by Environmental Manipulations

Kathryn Chanaberry&

Katy Underwood

Tank B2 Three Striped Damselfish

Dasyllus aruanus

Blue Devil Damselfish Chrysiptera cyanea

Background InformationCommonly referred to as the “feistiest of reef-

fish”, damselfish are a small, primarily tropical marine fish of the family Pomacentrid

Damselfish have been observed to display aggressive behavior towards anything that comes between them and their food. Similarly, damselfish aggressively guard their territories, spawns, and mates.

Background InformationThese aggressive behaviors include

prey/predator aggression, territory protection, mate and status protection, spawn protection, and opportunistic feeding behavior

The aggressive behaviors of damselfish are most commonly identified as chases, nips, approaches, submits, flees, and threats

Getting Started…What We Knew: Notoriously aggressive

Aggression can be triggered by numerous variables such as feeding, territory, and status protection

All which come in the form of chases, nips, approaches, submits, flees, and threats

Getting Started…What We WANTED to Know: 1. Considering that damselfish are territorial, how would

changing the layout of the tank affect aggression?2. How does eating encourage aggression between damselfish?3. Of the two damselfish in the tank, which fish is more

dominant and does that ever change? (Chrysiptera cyanea or Dasyllus aruanus)

4. Would adding an extra fish affect the dominance of the fish or the aggressive behaviors of the fish? How?

5. What specific variables influence the specific types of aggression- nipping, chases, flees, threats, submits and approaches?

Hypothesis

The aggressive behaviors of damselfish will be

influenced/triggered by environmental manipulation

of Tank B2.

Review of Wiki

Review of Wiki

Review of Wiki- Proposal CONT.

Review of Wiki- Monthly

Review of Wiki

Review of Wiki

Review of Wiki

What causes the specific types of aggression- nipping, chases, flees, threats,

submits and approaches?

Observe

Define

Behavioral Ethogram

What causes the specific types of aggression- nipping, chases, flees, threats,

submits and approaches?After observing the fish over a short period of time, we were able to come up with our definitions to describe and categorize the damsels’ aggressive behaviors. Nip- Nipping is when a fish gestures a bite toward another fish. Usually, when a fish nips, first it will demonstrate some other form of aggression first almost as a warning. For example: chasing or threats.Threat- A threat is an intimation method to warn other fish of its aggressive mood or tendencies. A threat is issued by flaring the gills in front of the other fish.Approach- An approach is another form of intimidation toward other fish. It is done at different speeds and angles, depending on the level of aggression the fish have. Approaches are used to set a tone of dominance amongst the other fish.

What causes the specific types of aggression- nipping, chases, flees, threats,

submits and approaches?After observing the fish over a short period of time, we were able to come up with our definitions to describe and categorize the damsels’ aggressive behaviors. Flee- A flee is a form of submission to a dominant or more aggressive damselfish. A flee is when a fish runs away from an overly aggressive fish. A fish may flee in reaction to a nip, approach or tail dig.Submit- A submit holds a bit more confidence than a flee, because it is also a form of submission to aggressive behavior, however, the fish will stand its ground. This behavior may occur in reaction to any higher aggressive behaviors.Tail Dig- A tail dig is a less common term describing the behavior when a damselfish sweeps its tail in the sand in an upward motion towards a nearby fish. This behavior is a fairly aggressive one used to ward off other fish and establish a sense of dominance.

What causes the specific types of aggression- nipping, chases, flees, threats,

submits and approaches?Behavioral Ethogram:

We initially wanted to use a behavioral ethogram to record not only the aggressive behaviors of the fish, but also where the fish were located in the tank.

Troubleshooting

We rarely witnessed the damsels display these behaviors on a daily observation. Ethograms were producing confusing data that was somewhat irrelevant to the overall goal of our project (which was more about environmental manipulations instead of defining aggressive behaviors).

Solutions(Project takes a turn for the better!)

Combine all of the behaviors we had defined and categorized them all as “aggressive behavior” During observations, instead of asking “what type of aggressive behaviors are happening”, we asked ourselves “is there any aggressive behavior” & “what is provoking it” Although we stopped using the ethograms, we did continue to observe and record the tank positions of the fish. This helped us take notice of the patterns of our damsels’ position in the tanks…which leads us to the major quantitative and qaulitativedata of our project.

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?

� Observe damsel’s positions and behavior in Tank Layout #1

� Remove Left Live Rock

� Observe damsel’s positions and behavior in Tank Layout #2

� Remove Right Live Rock

� Observe damsel’s positions and behavior in Tank Layout #3

� Compare and Contrast

How does eating encourage aggression between damselfish?

1. Observe feeding behavior during tank layout #12. Observe feeding behavior during tank layout #23. Observe feeding behavior during tank layout #3

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?Tank Layout #1

Right Live Rock

Center Live Rock Left Live Rock

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?

Striped Damsel Blue Damsel

Tank Layout #1

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?Tank Layout #2

Left Live Rock

Center Live Rock Right Live Rock

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?

Striped Damsel Blue Damsel

Tank Layout #2

http://www.youtube.com/watch?v=XIjrdaLtezo&feature=player_embedded

How does eating encourage aggression between damselfish?

Of the two damselfish in the tank, which fish is more dominant and does that ever change? (Chrysiptera cyanea or

Dasyllus aruanus)

Tank Layout #2:Blue Damsel’s

Hurt Tail

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?Tank Layout #3

Right Live Rock

Center Live Rock Left Live Rock Center Live Rock

Considering that damselfish are territorial, how would changing the layout of the tank

affect aggression?

Striped Damsel Blue Damsel

Tank Layout #3

How does eating encourage aggression between damselfish?

http://www.youtube.com/watch?v=qHTmIkULSlk&feature=player_embedded

Of the two damselfish in the tank, which fish is more dominant and does that ever change? (Chrysiptera cyanea or

Dasyllus aruanus)

Tank Layout #3:

Blue Damsel’s Tail has healed!

Reminder of WHERE Locations are in Tank B2

Compiled Data

ConclusionsAs you can see from the data we collected from

our observations and experimentation supports our original hypothesis that stated:

The aggressive behaviors of damselfish will be

influenced/triggered by environmental manipulation

of Tank B2.

What is the value of our results?

Not only has it taught us more about these fish and influenced our appreciation for their existence, but it supplements biologists who have researched and found the same results we have. For example…

1. In dominance, the bigger fish tends to be more dominant

2. Damsels are territorial3. Feeding increases aggressive behaviors

Bibliography Ebersole, John P. "Niche Separation of Two Damselfish Species by Aggression And Differential

Microhabitat Utilization." Ecology 66.1 (1985): 14-20.JSTOR. Web. 19 Oct. 2011.

"The Feistiest of Reef Fish-Damselfish ." Reef Briefs. San Pedro Sun , n.d. Web.19 Oct. 2011.

Hauter, Stan, and Debbie Hauter. "Saltwater Aquarium Fish Compatibility."Saltwater Aquariums . About, n.d. Web. 19 Oct. 2011.<http://saltaquarium.about.com/>.

Holbrook, Sally J, Graham E Forrester, and Russell J Schmitt. "Spatial Patternsin Abundance of a Damselfish Reflect Availability of Suitable Habitat."Oecologia 122.1 (2000): 109-120. JSTOR. Web. 19 Oct. 2011.<http://www.jstor.org/action/myJstorSettings>.

Myrberg, Arthur A, Jr. "Social Dominance and Territoriality in the BicolorDamselfish." Behaviour 41.3/4 (1972): 207-231. JSTOR. Web. 19 Oct. 2011.

"Animal Planet :: Fish Guide -- Damselfish." Animal Planet : Pets, Wild Animals, Dog Breeds, Cat Breeds. N.p., n.d. Web. 3 Feb. 2012. http://animal.discovery.com/guides/fish/marine/damselintro.html

"damselfish." Encyclop ｾ dia Britannica. Encyclop ｾ dia Britannica Online School Edition.Encyclop ｾ dia Britannica, Inc., 2012. Web. 29 ﾊ Apr. ﾊ 2012.

"perciform." Encyclop ｾ dia Britannica. Encyclop ｾ dia Britannica Online School Edition.Encyclop ｾ dia Britannica, Inc., 2012. Web. 29 ﾊ Apr. ﾊ 2012.

For NEXT YearWe suggest that whoever chooses tank B2,

combine our two experiments into ONE. Observe the specific aggressive behaviors in the

specific locations of the tank we created. See what aggressions are triggered WHERE and WHY.