Fish can survive without food for varying lengths of time depending on several factors, including the species of fish, age, health, and environmental conditions. Generally, many species of fish can go without food for a few days to a couple of weeks.
For smaller or newly hatched fish, the duration they can survive without food is usually shorter due to their higher metabolic rates. In contrast, larger and well-established aquarium fish can endure longer periods without feeding. For example, goldfish and bettas may last a week or more without food, while some hardy species can manage up to two weeks.
Environmental conditions play a crucial role in this timeframe. Fish that are in colder water tend to have slower metabolisms, enabling them to survive longer without food. Conversely, fish living in warmer waters may require more frequent feeding due to increased metabolic rates. Additionally, fish that are stressed or sick also tend to eat less and might not survive as long without food.
It's important to note, however, that while fish can survive for several days or weeks without food, prolonged periods of starvation can lead to weakened immune systems, stunted growth, and other health issues. Thus, it's advised to maintain a regular feeding schedule whenever possible, ensuring a balanced diet appropriate for the specific fish species you have.
If you temporarily cannot feed your fish, consider options to manage their environment better to minimize stress or reduce feeding frequency gradually rather than stopping abruptly. This can help maintain their health until feeding can resume.