Mas gusto ko ang isda kaysa manok sa hapunan.

In everyday Filipino, mas gusto is the normal way to say prefer.

• gusto = like / want
• mas = more

So mas gusto literally means like more. That is how Filipino usually expresses comparison of preference in ordinary speech.

Filipino pronouns change form depending on their role in the sentence.

• ako = the ang-form of I
• ko = the ng-form of I / my

With gusto, the person who feels the liking is commonly expressed with the short form ko:

• Gusto ko = I like / I want
• Mas gusto ko = I prefer

So ko is the expected form here.

Yes. This is a complete sentence.

The sentence is about preference, not the action of eating. In Filipino, you do not need to add a verb like eat if the idea is already clear from mas gusto plus the food items and the time phrase.

So the sentence is structurally complete as I prefer fish to chicken for dinner, even without an explicit eat.

Ang is a marker. It does not work exactly like English the.

Here, ang isda marks fish as the main noun phrase being talked about or highlighted in the sentence. In this comparison, fish is the item being presented as the preferred choice.

So:

• ang isda = the/topic noun phrase fish

A good learner habit is to think of ang as a marker, not as a direct translation of the.

Because manok is the second item in the comparison after kaysa.

In Filipino comparisons, the noun after kaysa is often left without ang:

• ang isda kaysa manok

That is normal. The first item is the one being highlighted as the preferred one, so it gets ang, while the second item does not have to.

Kaysa means than in comparisons.

So:

• isda kaysa manok = fish rather than / than chicken

It is the word that connects the two things being compared.

Yes. Mas gusto ko ang isda kaysa sa manok is also natural.

Both kaysa manok and kaysa sa manok are used. In everyday speech, many speakers use kaysa sa very often. The version without sa is also correct and common.

So both of these are fine:

• Mas gusto ko ang isda kaysa manok
• Mas gusto ko ang isda kaysa sa manok

This is a very common learner question because both patterns can appear with gusto.

Very roughly:

• Gusto ko ng isda often sounds like I want some fish or I like fish in a more non-specific sense.
• Gusto ko ang isda can sound more like fish is the thing I like / choose / prefer, especially when contrasting it with something else.

In this sentence, there is a clear comparison with manok, so ang isda works well because fish is being singled out as the preferred option.

Sa hapunan means for dinner or at dinner, depending on how you express it in English.

• sa is a very common marker that can correspond to English ideas like in, at, on, to, for
• hapunan = dinner / evening meal

So sa hapunan gives the context of the preference: this is the preferred food for dinner.

Putting it at the end is a natural, neutral word order.

The sentence first gives the main idea:

• Mas gusto ko ang isda kaysa manok
  then adds the situation:
• sa hapunan

Filipino word order is fairly flexible, so you could also say:

• Sa hapunan, mas gusto ko ang isda kaysa manok.

That version puts extra attention on for dinner.

Here it most naturally means fish as a food category in general, not one particular fish.

Likewise, manok here means chicken as food, not necessarily a live chicken. Context tells you that because of sa hapunan.

So the sentence is comparing two kinds of food, not two individual animals.

Yes. It is natural and understandable.

A speaker might also say slightly different versions depending on style, such as:

• Mas gusto ko ang isda kaysa sa manok sa hapunan.
• Sa hapunan, mas gusto ko ang isda kaysa manok.

But the original sentence is perfectly normal Filipino.