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

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

2. 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

3. Overview • Background Information • Hypothesis • Materials • Methods • Results • Discussion • Conclusions

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

5. Background information Neon Tetras (Cheirodoninnessi) • Small, bright, vulnerable to predation • Zebra fish (Daniorerio) • Aggressive • Territorial

6. 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

7. 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

8. Materials • Dip net • Aquarium • 500mL Jar • Neon tetras • Zebra fish

9. Materials • The Aquarium: 1 2 3 4

10. Materials • The Aquarium: Water temperature maintained at 20⁰C

11. 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

12. 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

13. Results • Small school:

14. Results • Small school: • Chi-square analysis • Experimental: X2(3)= 52.4, p<0.05 • Control: X2(3)= 38.3, p< 0.05 • Significant preference for section 3 • Mann-Whitney U • p >0.9999 • Insignificant difference between control and experimental

15. Results • Large school:

16. Results • Large school: • Chi-square analysis • Experimental: X2(3)= 45.3, p< 0.05 • Control: X2(3)= 12.0, p<0.05 • Significant preference for section 3 • Mann-Whitney U • p =0.8857 • Insignificant difference between control and experimental

17. 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

18. 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

19. 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

20. 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