Effects of school size of neon tetras on their response to the presence of a zebra fish Kelsey and Jenna

Purpose of the experiment Look at schooling behaviour in neon tetras in the presence of a predator, measured in terms of distance from a predator

Overview Background Information Hypothesis Materials Methods Results Discussion Conclusions

Background Information Schooling: anti-predator strategy – Predator confusion – More fish reduces individual’s chance of attack – More energy invested in feeding and mating

Background information Neon Tetras (Cheirodon innessi) – Small, bright, vulnerable to predation Zebra fish (Danio rerio) -Aggressive -Territorial

Background Information Neon tetras display schooling behaviour Zheng et. al. – Presence of unfamiliar object – Increase in school size, decrease in timidity Darting Time between feeding Sloman et. al. – Presence of aggressive fish – Increase in schooling

Hypothesis The neon tetras would remain further away from the zebra fish when the neon tetras were present in a small school compared to a large group

Materials Dip net Aquarium 500mL Jar Neon tetras Zebra fish

Materials The Aquarium: 1234

Materials The Aquarium: Water temperature maintained at 20⁰C

Methods Neon tetras placed in aquarium – School sizes: 2 and 8 – Acclimation period of 3 minutes Jar containing a zebra fish added in section 4

Methods Scan sampling – Neon tetras in each section recorded every 30 seconds – Total of 15 minutes – 10 replicates for each school size – Control Empty jar 5 replicates for each school size

Results Small school:

Results Small school: – Chi-square analysis Experimental: X 2 (3)= 52.4, p< 0.05 Control: X 2 (3)= 38.3, p< 0.05 Significant preference for section 3 – Mann-Whitney U p > Insignificant difference between control and experimental

Results Large school:

Results Large school: – Chi-square analysis Experimental: X 2 (3)= 45.3, p< 0.05 Control: X 2 (3)= 12.0, p< 0.05 Significant preference for section 3 – Mann-Whitney U p = Insignificant difference between control and experimental

Discussion Due to insignificant difference between control and experimental, hypothesis could not be accepted or rejected Jar was seen as a novel object – Saxby et. al. Higher prevalence of darting in presence of unfamiliar object when in small schools

Discussion Predator did not cause neon tetras to stay away Possible reasons: – Wanted to school with the zebra fish – Zebra fish was not threatening enough Zebra fish normally school Separation by the jar – Curiosity of the neon tetras

Discussion Future avenues of research: – Looking at darting behaviour – Use a more aggressive species Ex: Angelfish – Using a model predator – Trials without the jar – Collecting more data

Conclusions No significant difference in the response to the empty jar versus the predator Neon tetras were attracted to the jar, despite the size of the school Future improvements to the data collection could provide more useful results