Nevertheless, one potential source of error in this experiment was when transitioning between different trials, the Betta splendens intruder fish did not rest for a 24-hour period as they were just used in the previous trials. As a result, the state of the Betta splendens intruders was not certain, and the fish possibly behaved more aggressively after seeing other Betta splendens fishes. In future experiments, the intruder fish should rest for 24 hours after every trial so they can be in a calm state. In addition, a possible source of error was when conducting the experiments, the sounds of moving in a chair or banging the table with the legs would impact the state of the fish, they will possibly panic and display abnormal behavior during the trials, which decreases the reliability of the data. A solution to solve this issue is to be gentler and more careful when sitting on chairs and tables when recording the data. Lastly, the concentration of the fish was not consistent. After the first day of the experiment, the water with the caffeine concentration evaporated, and some caffeine was evaporated along the process. In future experiments with more time to conduct trials, experimenters should make new concentrations every trial to ensure the consistency of the water of each experimental group.