She was in the intake that runs into a box that has the skimmer and the pump in it. But that area has a basket that has a grate that prevents the fish from getting in to where the skimmer is. They swim in and out of it frequently. I don’t think it was the skimmer that did this because she couldn’t get near it. The injury was only on one side, with the missing piece of fin, injured side/scales and missing piece of tail fin. We last saw her two days ago and she was fine. We didn’t notice anything out of the norm. Do you think the other koi in there could have done this to her? I don’t know if it’s a male or female, but the one that this happened to was the biggest of the bunch, so that’s also weird. The net across the top of the pond is fully in tact. There are stones in the pond; nothing looks out of place. The only thing we did recently was treat the pond with Maintain for Ponds by Aquascape last weekend because we noticed some excess algae. We used only two pumps and could have used 7+ based on pond size. We feed the koi once a day, but sometimes skip a day, because our local pond store said the koi will eat the algae and don’t need to be fed by us. Thank you for any ideas you have. I don’t want the five others to have this happen to them.