Can you please tell me why the bigger goldfish’s respiratory rate is slower than the smaller goldfish?

Hi Mike!

A fish’s respiratory rate is dependent on several factors. Essentially, how much oxygen a fish consumes per breath depends on the mass of the fish, the temperature of the water, their respiratory health status, and their basal metabolic rate which is determined by their stress level and digestion. Any one of these factors will create variation in the “normal” rate.

Assuming their respiratory function is healthy (your fish does not have asthma), to get the most accurate test results, make sure your fish are the same for all factors except their mass. For example, you may want to separate the fish. Keep them in their own environments. That way, you know they are not causing stress for each other. Take your measurements at the same time of the day, before feeding, so that their metabolism will be at its base rate. Also, keep them in the same size containers and in the same room so that their water temperature will be comparable. Again, you want to make everything the same as much as possible.

This will ensure that you are only testing how their size affects their respiratory rate. Some studies have shown that the greater the mass of the fish, the more oxygen it will consume in a given time period. However, to verify this association, you must control for all variables other than mass and make precise and accurate measurements.

Good luck on your project! Have fun!!