Riley Palazzo

Document Type

Honors Thesis

Major

Marine Science

Advisor(s)

Heather Hamlin

Committee Members

Scarlett Tudor, Gail Schwieterman

Graduation Year

May 2025

Publication Date

2025

Abstract

Siamese fighting fish (Betta splendens) have been selectively bred for eye-catching color patterns and fin morphologies since the early 20th century. They are a member of the anabantoids, a group of air-breathing freshwater fish possessing a labyrinth organ that allows them to extract oxygen from the air and also influences many social behaviors. Both males and females will flare their gills as a mating behavior. Opercular displays prevent the flow of oxygen across the gills, but the labyrinth organ allows them to continue respiring. We understand B. splendens’ courtship behavior in the wild, but a more concrete understanding of whether or not generations of selective breeding has had a noticeable impact on such behaviors is necessary. Bettas have been an ideal model for applied research in many fields because of their unique morphology, behavior, and evolutionary history. Mate preference is often used to draw conclusions about changes in behavior given particular conditions. Without a reliable understanding of whether farmed and wild betta behavior has diverged, accurate conclusions cannot be confidently made. This study aims to draw definitive conclusions about mate preference behavior and whether color plays a significant role in mate selection. Attributes and behaviors like body size, nest size, and parental behavior all play an important role in mate selection in the wild, but in a lab setting where these factors are controlled, it is necessary to understand where coloration lies in importance for mating. Neither red nor blue females in this study showed a significant preference for males matching their own color or a preference towards red males as a whole. These results call into question the idea that color plays an important role in betta fish mate preference and selection, and thus further research is needed to either support or discredit them.

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