I am doing a project on sexual selection (male-male competition) in the turquoise killifish Nothobranchius furzeri.
There are two morphs of male in the population from which my fish are obtained from- one has a red tail and the other has a yellow tail.
My null hypothesis is: Tail colour is not related to dominance/competitive ability.
I will be putting one yellow-tailed male and one red-tailed male in an arena and recording the number or aggressive interactions that take place within 5 minutes and the winner of each. I have 8 red males and 8 yellow males all of similar colour intensity. I originally thought I had about 30 of each and I was going to rank for size and pair them up (i.e. largest red with largest male etc.)which would control for size (the larger fish are more dominant). However with a sample size of only 8 this would not be sufficient to get significant results.
How could I redesign the experiment and which statistical tests could I use?
I don’t have access to any more fish.