My fish has eaten another what shall i do?

It's heartbreaking to see your fish eat another. I understand you're concerned. To help you best, I need more information:

Tell me:

* What kind of fish are you talking about? Different species have different behaviors.

* What fish did it eat? Was it a smaller fish or a tank mate?

* How big is your tank? A crowded tank can lead to aggression.

* How many fish are in the tank? Overstocking can lead to stress and aggression.

* What are the water parameters? (Temperature, pH, ammonia, nitrite, nitrate)

* How long have you had the fish?

Once you provide these details, I can give you more specific advice on what to do.

In the meantime, here are some general tips:

* Separate the fish immediately: If possible, isolate the aggressive fish to prevent further harm.

* Observe the remaining fish: Watch for signs of injury or stress.

* Check water quality: Poor water quality can lead to aggression.

* Consider your tank setup: Are there enough hiding places for the fish?

* Research the specific needs of your fish: Some species are naturally more aggressive than others.

Please provide more information so I can help you further.