Although ceramic aquarium cups are relatively durable, they still need to be replaced over time:

First, noticeable damage or cracks appear on the surface of the ceramic cup. If these are found, it needs to be replaced immediately. These damages can easily lead to leaks or the introduction of parasites and other harmful substances into the aquarium.

Second, severe stains appear on the surface. Once stubborn stains appear on the surface of the ceramic aquarium cup, bacteria and algae can easily grow, affecting not only the aesthetic appeal but also the health of the fish.

Third, accelerated aging. If you notice that the ceramic aquarium cup is aging significantly faster than expected, consider replacing it with a new one to avoid impacting the health of your fish.