Piscis hamum mordet.

Because hamum has the ending -um, which marks it as accusative singular here, so it is the direct object: the thing being bitten.

That leaves piscis as the subject: the one doing the biting.

So:

• piscis = the fish / a fish → subject
• hamum = the hook / a hook → direct object

In Latin, case endings often tell you the job of a word more clearly than word order does.

In this sentence, piscis is nominative singular, because it is the subject of mordet.

The noun is:

• piscis, piscis = fish

This is a third-declension noun, and its nominative singular happens to be piscis.

A beginner may notice that piscis can also be the genitive singular form in a dictionary entry, but in this sentence it functions as the nominative subject.

Because hamum is the direct object of the verb mordet.

The verb mordere means to bite, and the thing that gets bitten is put in the accusative case in Latin.

The noun is:

• hamus, hami = hook

Its accusative singular is:

• hamum

So hamum means the hook or a hook as the object of the verb.

Because the subject piscis is singular and third person: the fish bites.

The verb is from:

• mordeo, mordere = to bite

Here, mordet is:

• present tense
• indicative mood
• active voice
• third person singular

So it means:

• he/she/it bites

Since piscis is a singular noun, the verb must also be singular.

In Latin, the personal ending on the verb shows who is doing the action.

The ending -t means he/she/it in the present tense.

So:

• mordet = he/she/it bites

English often needs a separate subject pronoun like it, but Latin usually does not, because the verb ending already tells you the person and number.

No. Classical Latin has no articles like English the or a/an.

So:

• piscis can mean a fish or the fish
• hamum can mean a hook or the hook

Which one sounds best depends on context. Without more context, Latin leaves that unspecified.

It is somewhat important for style and emphasis, but not as important as in English for basic meaning.

Because Latin uses case endings, you can often change the order without changing the core meaning. For example, all of these could mean the same thing:

• Piscis hamum mordet
• Hamum piscis mordet
• Mordet piscis hamum

The endings still show that:

• piscis is the subject
• hamum is the object

That said, subject-object-verb is a very common and natural Latin order, so Piscis hamum mordet is a straightforward sentence.

They are:

• piscis, piscis (masculine) = fish
• hamus, hami (masculine) = hook
• mordeo, mordere, momordi, morsum = bite

For nouns, Latin dictionaries usually give:

• the nominative singular
• the genitive singular
• the gender

For verbs, dictionaries usually give the principal parts, which help you form different tenses and stems.

Because nouns belong to different declensions, which are patterns of case endings.

• hamus belongs to the second declension
• piscis belongs to the third declension

You simply learn each noun with its dictionary forms, and those forms tell you which pattern it follows.

For example:

hamus, hami

• nominative singular: hamus
• accusative singular: hamum

piscis, piscis

• nominative singular: piscis
• accusative singular: piscem

So if fish were the object, it would be piscem, not piscis.

Yes, piscis can also be the genitive singular form, meaning of the fish, depending on context.

But not here.

In Piscis hamum mordet, the sentence structure shows that piscis is the subject:

• hamum is clearly accusative
• mordet needs a subject
• so piscis is understood as nominative singular

This is a good example of how Latin learners must use both form and context.

A common classroom pronunciation would be roughly:

• PIS-kis HA-mum MOR-det

More carefully in restored classical pronunciation:

• piscis = PIS-kees or PIS-kis depending on teaching tradition
• hamum = HA-mum
• mordet = MOR-det

A few helpful points:

• c is always hard, like k
• h is pronounced lightly
• e in mordet is like e in met, not like English ee

It usually does not need to be added, because mordet already means he/she/it bites.

If you wanted extra emphasis, Latin could use a pronoun, but in a simple sentence like this it would normally be omitted.

So Latin naturally says:

• Piscis hamum mordet

not something like:

• It fish the hook bites

Latin relies much more on endings than English does.

It is in the present tense.

• mordet = bites / is biting

So the sentence describes an action happening in the present, or a general fact stated in the present.

Depending on context, it could mean:

• The fish bites the hook
• A fish is biting the hook
• The fish is biting the hook

Latin present tense can cover both simple present and present progressive ideas that English often distinguishes.