They need an independent variable, in this case it should have been the fish food. Everything should be identical except the fish food, from what I read , it doesn't say anything about what type of food they used, or the dosage.
Answer:
Fossil records help scientists understand about how and when an organism might have evolved. It also helps determine how many evolutionary changes a particular specie might have gone through.
The long-term evolutionary patterns for a specie can be determined by fossils. Fossil record will help us analyze all the evolutionary changes that a species might have gone through to evolve into a particular type.
The gradual evolution of a species can be predicted if the fossil records show small, increment changes in the fossil patterns.
On the other hand, rapid evolution will result when there are no intermediate fossils depicted for a specie. That specie might have aroused due to a sudden change.
