Eu prefiro peixe bem temperado.

Yes, you often can leave out eu in Portuguese.

Prefiro peixe bem temperado is a perfectly natural sentence because the verb form prefiro already shows that the subject is I.

Including eu can:

• add emphasis: Eu prefiro..., not someone else
• add clarity in context
• sound more explicit

So both are correct:

• Eu prefiro peixe bem temperado.
• Prefiro peixe bem temperado.

In everyday Brazilian Portuguese, dropping the subject pronoun is very common.

Prefiro means I prefer.

It comes from the verb preferir = to prefer.

This is the 1st person singular form in the present tense:

• eu prefiro = I prefer
• você prefere = you prefer
• ele/ela prefere = he/she prefers
• nós preferimos = we prefer
• vocês preferem = you all prefer
• eles/elas preferem = they prefer

A useful pattern to remember is:

• preferir algo = to prefer something
• preferir algo a outra coisa = to prefer something to something else

Example:

• Prefiro peixe a carne. = I prefer fish to meat.

In Portuguese, articles are often used differently from English.

Here, peixe without an article has a more general meaning:

• Eu prefiro peixe bem temperado. = I prefer well-seasoned fish.

It means fish as a type of food, not one specific fish.

If you say o peixe, it can sound more specific:

• Eu prefiro o peixe bem temperado. = I prefer the fish well-seasoned / I prefer fish when it is well seasoned.

So:

• peixe = fish in general
• o peixe = a more specific or more definite fish/fish category in context

It is singular because it describes peixe, which is singular.

In Portuguese, adjectives usually agree with the noun in gender and number.

Here:

• peixe = singular
• temperado = singular masculine form

If the noun changed, the adjective would change too:

• peixes bem temperados = well-seasoned fish
• carne bem temperada = well-seasoned meat
• carnes bem temperadas = well-seasoned meats

So temperado matches peixe.

Both exist, but they do not mean exactly the same thing.

• bem temperado = well seasoned
• muito temperado = very seasoned / heavily seasoned

In this sentence, bem works like well in English. It suggests the fish is seasoned properly or nicely, not just excessively.

So:

• peixe bem temperado = fish seasoned in a good way
• peixe muito temperado = fish with a lot of seasoning

This is an important difference in Portuguese:

• bem often expresses quality
• muito often expresses quantity or intensity

Here, temperado means seasoned.

It comes from temperar, which means:

• to season food
• to add seasoning, spices, salt, herbs, etc.

So peixe bem temperado means fish that has been seasoned well.

Be careful not to confuse it with English tempered, which usually has a different meaning. In food contexts, temperado is very commonly seasoned.

The natural word order is:

• Eu prefiro peixe bem temperado.

In Portuguese, the adjective often comes after the noun, especially in a straightforward descriptive phrase.

So:

• peixe bem temperado = well-seasoned fish

Eu prefiro bem temperado peixe sounds unnatural in normal Brazilian Portuguese.

You might also hear slight variations depending on emphasis, but the standard, natural order here is:

• verb + noun + modifier
• prefiro peixe bem temperado

A simple approximate pronunciation for an English speaker is:

eh-oo preh-FEE-ro PAY-shi beng tehm-peh-RAH-do

A few notes:

• eu often sounds like eh-oo or even more smoothly blended
• prefiro has stress on fi: pre-FI-ro
• peixe sounds roughly like PAY-shi
• bem ends with a nasal sound; it is not exactly bemm
• temperado has stress on ra: tem-pe-RA-do

If you want a rougher Brazilian rhythm, think:

• Eu prefiro → flows together smoothly
• peixe bem temperado → stress mainly on pei and ra

Yes. Both are possible in English, but I prefer well-seasoned fish sounds more natural.

That matches the Portuguese structure very well:

• peixe bem temperado = well-seasoned fish

A more literal translation like I prefer fish well seasoned is understandable, but less natural in everyday English.

Yes, but it usually needs context.

For example:

• O que você quer comer?
• Prefiro peixe.

That means:

• What do you want to eat?
• I prefer fish.

So prefiro can stand alone when what is being preferred is already understood.

You can also expand it:

• Prefiro peixe.
• Prefiro peixe bem temperado.
• Prefiro peixe a carne.

Yes, it is natural and correct in Brazilian Portuguese.

A Brazilian speaker might also say:

• Prefiro peixe bem temperado.
• Eu gosto mais de peixe bem temperado.
• Prefiro peixe quando está bem temperado.

These have slightly different nuances:

• prefiro = I prefer
• gosto mais de = I like ... more
• quando está bem temperado = when it is well seasoned

But your original sentence is completely natural and idiomatic.