While it might seem like "ichthyology" (the study of fish) would be the answer, hydrobiology encompasses a broader range of aquatic organisms, including:
* Fish
* Invertebrates (like crustaceans, mollusks, and insects)
* Amphibians
* Reptiles (like sea turtles and crocodiles)
* Marine mammals (like whales, dolphins, and seals)
Hydrobiology focuses on the interactions between these animals and their aquatic environment, including:
* Ecology (relationships between organisms and their surroundings)
* Physiology (how organisms function)
* Behavior
* Conservation
So, hydrobiology is the most accurate term for the study of aquatic animals in all their diversity!