an injury

Question
i have 2 koi in a tank they are not to large yet, one of my koi banged his side on the filter he has what looks like a bruise now the other one is nipping at the spot will that kill the injured one ?

Answer
Hi Michelle,
There would be a chance that it would die if it is a big injury.  Especially if the other fish are causing it to stress such as the nipping.  Add Melafix to the water, it is specifically made to heal wounds.  If you are not keeping live plants or any invertebrates you can add aquarium salt also, it is gives off electrolytes that is very beneficial for the fish.  Also keep up with the water changes, top notch water encourages health and healing.

Good luck with the kois and hope everything works out well.
-Matt-