I apologize in advance, my knowledge in statistics is pretty basic. I wonder if a repeated measures ANCOVA would be a good approach in my case.
I have two species of fish and I want to test if their activity response to a contaminant is different. So I will measure repeatedly over time (up to 3 hour-exposure) the activity of 5 individuals of each species in the presence of the contaminant. I guess exposure time will be the covariate. Activity is measured with telemetry tags that deliver an activity read every 5-10 minutes (so time points are not exactly the same for each individual fish).
Since I do not know whether there is a linear relationship between exposure time and activity, would be adequate to use a repeated measures ANCOVA?? And how should individual fish-effects assessed?