Anyone asking this is usually holding a nail up against a description and hoping the two match. So the exact wording of the description deserves a slow read before you decide anything.
The description, word for word
Cleveland Clinic gives the plainest version: "With toenail fungus, your nail becomes thick and yellow and may show white spots and streaks."
Read the verbs. "Becomes thick and yellow" is stated without hedging. "May show white spots and streaks" is not, so white marks are described as a possibility, not a requirement.
What the sentence does not cover
It describes how a nail looks. It does not tell you how to confirm what you are looking at, and it does not say what a clear nail should look like. For the medical side, these pages file the subject under onychomycosis: the AAFP entry on nail fungus, a PubMed Central review titled "Onychomycosis: Old and New", and Cleveland Clinic's causes and treatment page.
What to confirm, and with whom
Take the nail itself, or a clear photo of it, to a foot doctor near Itasca and ask two things: what do you see, and how do you know. A look in the mirror cannot answer the second question.
The word readers skip
The word is "may." A nail that is thick and yellow fits the description. A nail with no white spots still fits it too.