Yes, fish curry should be cooled completely before freezing to prevent bacterial growth and maintain its texture and flavor. Cooling it rapidly is also recommended.
Freezing food while it's still warm can create several problems. Firstly, it raises the temperature inside your freezer, potentially thawing other frozen items and compromising their quality. Secondly, slow cooling in the center of a large container of warm curry creates a breeding ground for bacteria. Cooling the curry quickly minimizes the time it spends in the 'danger zone' (between 40°F and 140°F), where bacteria multiply rapidly. To cool the curry effectively, divide it into smaller portions in shallow containers. You can also use an ice bath: place the containers in a larger bowl filled with ice water, stirring occasionally to speed up the cooling process. Once the curry is completely cool, it's safe to transfer it to the freezer. Properly cooled and frozen fish curry will maintain its flavor and texture much better.
When reheating frozen fish curry, thaw it in the refrigerator overnight for the best results. Avoid thawing at room temperature, as this can again promote bacterial growth. Reheat thoroughly until it reaches an internal temperature of 165°F (74°C).