Based on a journal article entitled "'Love at first sight': The effect of personality and colouration patterns in the reproductive success of zebrafish (Danio rerio) by Vargas et al. (2018), identify and list relevant information for each of the following elements:

1. Research hypothesis or research question or problem statements
2. Treatments (factors), level and range (interval)
3. Experimental (observational) units
4. Sample size and replication
5. Response variable
6. Types of experimental design (include the criteria for any grouping, blocking, or pairing done, if applicable)