The mode of nutrition in Fungi is heterotrophic.

Explanation:
There are broadly two types of nutrition on earth namely autotrophic and heterotrophic.
Autotrophic are the ones which can produce food themselves say by photosynthesis.
Heterotrophic are the ones which depend on other organisms for nutrition.

As fungi cannot produce their own food and depend on others, they are heterotrophic.

Moreover, Heterotrophic nutrition is also classified into
1. Holozoic
2. Saprophytic
3. Parasitic.

Fungi come under saprophytic nutrition which is that they obtain nutrition from non-living organic matter.