Aquarium diagnostic in the NYT crossword refers to the answer "PHTEST," a six- letter solution that appeared for the clue on the NYT puzzle dated October 29, 2025.

If you’re solving today’s NYT crossword and the clue is similar, the expected entry is likely PHTEST. Here’s a quick check you can use while solving:

• Aquarium diagnostic is a playful phrase that leads to the six-letter abbreviation PHTEST.

• Several solver sites and puzzle recap pages confirm the same six-letter answer for that date.

Would you like a quick explanation of why that clue points to PHTEST, or help with the surrounding clues in the same puzzle?