He threw in a huge amount of money like a boat-swallowing fish to make the project successful.

This restaurant uses substitute fish when expensive types of fish are not available.

This carnivorous fish eats other small fish.

Reeves' shad is a fish commonly seen in rivers in Japan.

He is learning Ancient Greek language.

I am majoring in microbiology at university.

Astrobiology is a very interesting field of study.

I am majoring in microbiology at university.

He is an expert in paleontology.

He is an expert in aerobiology, engaged in the study of microorganisms in the atmosphere.