Fiskekortet viser ikke engang krokstørrelsen.

Because fiskekortet is the definite singular form of fiskekort.

• et fiskekort = a fishing permit / a fishing card
• fiskekortet = the fishing permit / the fishing card

The ending -et is the definite article for many neuter nouns in Norwegian.
So instead of adding a separate word like the, Norwegian often adds the definiteness to the end of the noun.

It is a compound noun:

• fiske = fishing
• kort = card

So fiskekort literally means fishing card, but in practice it usually means a fishing permit / fishing licence / fishing pass, depending on context.

Compound nouns are very common in Norwegian, and they are normally written as one word.

Because it means the hook size, not just a hook size or hook size in general.

Breakdown:

• krok = hook
• størrelse = size
• krokstørrelsen = the hook size

In this sentence, the speaker is talking about a specific piece of information that should be shown, so the definite form sounds natural.

Compare:

• viser krokstørrelse = shows hook size / shows information about hook size more generally
• viser krokstørrelsen = shows the hook size, the specific size being referred to

Because Norwegian usually puts the onto the noun itself.

So:

• the fishing permit → fiskekortet
• the hook size → krokstørrelsen

This is normal in Norwegian. English uses a separate article; Norwegian often uses a suffix.

You only get an extra determiner in some cases, especially with adjectives:

• boka = the book
• den store boka = the big book

But here there are no adjectives, so the suffix alone is enough.

Because in a normal Norwegian main clause, the finite verb usually comes in second position. This is the famous V2 word order.

Here the sentence pattern is:

• Fiskekortet = subject
• viser = finite verb
• ikke engang = adverbial
• krokstørrelsen = object

So the order is natural: Fiskekortet viser ikke engang krokstørrelsen.

This is similar to many Norwegian sentences where ikke comes after the verb in main clauses:

• Han kommer ikke.
• Vi forstår ikke dette.

Ikke engang means not even.

It adds emphasis. It suggests that the thing mentioned is something you would at least expect to be included, but it is missing too.

So:

• Fiskekortet viser ikke krokstørrelsen. = The fishing permit does not show the hook size.
• Fiskekortet viser ikke engang krokstørrelsen. = The fishing permit does not even show the hook size.

The second version sounds stronger and more critical.

Yes, here engang is part of the expression ikke engang = not even.

That is different from en gang meaning once or one time.

Compare:

• Jeg var der en gang. = I was there once.
• Jeg har ikke engang vært der. = I haven’t even been there.

So in your sentence, engang is not about time. It is an emphasis word meaning even in a negative sentence.

Sometimes speakers move adverbs around in casual speech, but ikke engang is the most standard and neutral placement here.

The natural version is:

• Fiskekortet viser ikke engang krokstørrelsen.

You may sometimes hear things like:

• Fiskekortet viser ikke krokstørrelsen engang.

That can sound more spoken or colloquial. For a learner, ikke engang before the object is the safest pattern to remember.

Viser is the present tense of å vise = to show.

Forms:

• å vise = to show
• viser = shows / is showing
• viste = showed
• har vist = has shown

So your sentence is in the present tense: Fiskekortet viser ikke engang krokstørrelsen.

A past version would be: Fiskekortet viste ikke engang krokstørrelsen.

Because Norwegian normally places sentence adverbs like ikke before the object in main clauses.

So this pattern is very common:

• subject + verb + ikke
  • object

Examples:

• Jeg kjøper ikke boka.
• Han forstår ikke spørsmålet.
• Fiskekortet viser ikke engang krokstørrelsen.

Putting the object earlier would usually sound unnatural in a plain statement.

Yes. In a subordinate clause, ikke usually comes before the verb.

Main clause:

• Fiskekortet viser ikke engang krokstørrelsen.

Subordinate clause:

• ... at fiskekortet ikke engang viser krokstørrelsen.
• ... because the fishing permit doesn’t even show the hook size.

So this is a useful contrast:

• Main clause: verb before ikke
• Subordinate clause: ikke before verb

That is a very important Norwegian word-order rule.

Yes, but the meaning or nuance would change.

• krokstørrelsen = the hook size, a specific expected detail
• krokstørrelse = hook size, more general or less specific

In your sentence, the definite form sounds more natural because the speaker is referring to a particular required piece of information on the permit. Using the indefinite form would feel more general and a bit less idiomatic in this context.

So krokstørrelsen is probably the better choice here.