Siamese fighting fish (Suborder Anabantoidei) have long been valued by aquarists for their brilliant colors, ornate fin shapes, and stylized behavioral displays. Originally from Thailand, virtually all of the Siamese fighting fish sold in pet stores are males that were bred specifically for these traits. Despite this artificial selection, domesticated fish (Betta splendens) retain many of the behavioral and morphological characteristics of their wild counterparts.

Wild Betta thrive in warm (25 - 28 °C), often brackish pools and rice paddies. They tolerate the low-oxygen conditions in these habitats by slurping air directly from the atmosphere into a specialized respiratory organ called a "labyrinth". This adaptation allows them to persist in areas where many other species, particularly potential predators, cannot. This release from predation pressure undoubtedly contributed to the evolution of gaudy male colors and behaviors.

During mating, males build a "bubble nest" that they defend from other males by means of threat displays and extremely aggressive butting and biting (hence their name). While such encounters are rarely fatal, they can cause serious injury or leave combatants severely tattered. Males also use their colors and fins to court gravid females. Receptive females eventually choose a specific male and release their eggs on and near the nest. Males fertilize these eggs and gather them all into the nest. They then guard the eggs until hatching (24-36 hours later), again using aggressive displays to repel intruders. Thus, their behavioral displays have a variety of important functions that have direct relevance to an individual's reproductive success (= strong selection).

Past work has shown that the behavioral displays of Siamese fighting fish, though largely innate, may be induced by a variety of stimuli. The simplest of these (known as a sign stimulus) will still elicit a full display or "Fixed Action Pattern" (FAP). Over several weeks, you have a variety of props at your disposal (including another Betta) that will allow an investigation of the nature of these stimuli and the FAP, including how display intensity may wane with repeated exposure to certain stimuli (habituation).

Your investigations of the behavior of these fish will cover several weeks of lab time. During the first week you will generate an "ethogram", or behavioral profile, for individual fish. The results of these observations will be pooled to evaluate levels of inter-individual variation for this species and whether there is any correlation of this variance with phenotype. In the second week of the lab you will build off the results from the first week by developing and then implenting a protocol to evaluate what kinds of minimal stimuli are necessary to release the displaying behavior of Betta splendens.

Virtually all studies of behavior require an understanding of the behavioral repetoire an animal may exhibit. Only after specific behaviors have been identified with clear and objective criteria that discriminate one behavior from another can the process of quantifying behaviors, and the context in which they occur, be undertaken. To this end, behavioral scientists have developed a variety of protocols that ultimately provide an inventory of an animal's behaviors. The collective results of such an inventory is often called an "Ethogram".

Ethograms generally fit into two broad categories... those that describe behaviors on the basis of the behavior itself (e.g, postures, movements, sounds, etc) and those that describe behaviors in terms of their consequence (e.g., food acquistion, mating, fleeing a predator, etc). The same behavior can be judged using either category. For example, an observation of someone opening a door could be described as a behavior associated with "gaining entry to a room" or it could be described as "grasping and twisting a doorknob one-half turn then pushing inward". The former is a consquence, the latter is a discription of the behavior itself.

For this first week of work with Betta splendens you will construct an Ethogram of their behavior under two circumstances. First you will observe the fish in an environment lacking obvious external stimuli. Then you will observe the fish in the presence of a stimulus predicted to elicit an aggressive display behavior. Your goal will be to develop clear behavioral criteria that will distinguish between behaviors associated with an unstimulated condition and those that reflect a response to a stimulus.

Protocol:

1) You will work in pairs or teams of three. For the first week, each team will focus on a single fish for observation and data collection. To begin, each team should observe their fish and note traits that might be helpful for identifying this fish relative to others.

2) Before exposing the fish to any external stimuli, spend at least ten minutes observing its activities. What does the fish do? Does your presence seem to affect the fish? What measurements would allow you to quantify their behavior under these conditions? Try to identify categories of behavior that are exclusive from other behaviors (i.e., behaviors within a category don't overlap with each other... for example, horizontal movement might be broken down into three categories: no movement, left movement, right movement). Write down as many as you can. A brief discussion among the lab will seek to identify the range of behaviors shown by these fish.

3) Based on this discussion work with your lab partner to develop a protocol that will provide a time budget for the fish for at least two behavioral categories. Watch the fish for 3 x 5 minute periods, recording data on the occurence and duration of the behaviors within these categories.

3) Now, gently place the mirror in front of the fish and observe its behavior for five minutes. What changes in behavior do you see in your test fish during this time? Record your basic observations. Remove the mirror after five minutes and continue your observations for another five minutes. How does the fish respond when the external stimulus is no longer present? We will have another lab-wide discussion at this point to identify various features of the fish's behavior in the presence and absence of stimuli.

4) Based on observations and discussion, spend a few minutes working with your partner. Design a protocol for eliciting and quantifying the range of behaviors typically displayed by a male Siamese fighting fish when he encounters another male (in this case, its mirror image). Identify at least two behaviors that can be easily recognized and quantified (in whatever units of measurement you wish), then design a data sheet, either in your notebook or on the computer, that will allow you to record your observations. Allow at least 30 minutes to conduct these tests. Remember that habituation may influence your results, so recording the time, as well as any patterns of display, will be important. Show your protocol to the instructor before proceeding.

5) Follow the protocol you developed in 4 (above).

6) After these trials are finished, look at your data and see what patterns emerge. Do you see evidence of habituation. How do your observations compare with others in the class? Were the results similar, or were there obvious differences among different fish? How could you demonstrate this graphically and/or statistically? A discussion amongst the class will set the stage for next week's study.

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