A fish is a noun. To fish is a verb.
And is a conjunction.
In that sentence your is an adjective, or a possessive pronominal adjective.
The word fishing is a verb. It is the present participle of the verb fish.
Tuna is a noun. Nouns are the names of / places / things. Tuna is a thing (fish).
The word "species" is a noun. Here is an example of its usage in a sentence: There are over 28,000 species of fish on the planet.
Large is an adjective. In this sentence it is describing the noun fish and is part of the subject (large fish) of the sentence.
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The word bonito is a noun. A bonito is a type of fish.