The rate of breathing in aquatic animals/ organisms is much faster than that seen in terrestrial organisms. This could be attributed to :

The rate of breathing in aquatic organisms is significantly faster than in terrestrial organisms due to the lower concentration of dissolved oxygen in water compared to the oxygen levels in the atmosphere. In freshwater, the average concentration of dissolved oxygen is approximately 0.01% by weight, which is nearly 50 times lower than the concentration of oxygen in an equivalent volume of air [2]. Additionally, oxygen diffuses much more slowly through water than through air [1]. Because the availability of oxygen is much lower in aquatic environments, organisms like fish must move water over their gills more rapidly to extract the necessary amount of oxygen required for survival [3]. Terrestrial organisms, having access to an oxygen-rich atmosphere, do not need to breathe as rapidly to meet their metabolic demands [3].

Sources

1. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 4: Aquatic Ecosystem > Dissolved oxygen: > p. 34
2. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.6 > p. 89
3. [3] https://www.sciencedirect.com/science/article/pii/S1095643315002755