My Fish Seem Like They're Fighting, or Picking on One Fish in Particular.
They're actually NOT fighting. They are attempting to breed. Yep, your fish are gettin' busy. The males in the pond are trying to get the female to release her eggs into the water so that they can be fertilized. It does look like a brutal process to an outsider or first-time pond owner, but it's simply the fish's process of procreation. The female actually requires a bit of help from the males to release her eggs that have developed inside of her. She may look a little worse for wear for a short time, but should recover fairly quickly once the eggs are released, which brings us to the next issue...
Why is there foam in my pond?
The wise old owl told Bambi that every living creature gets "twitterpated" in the Spring. Well, your fish are living creatures! If you've noticed a foaming in your pond that comes and goes, don't panic. It's simply your fish responding to Spring's siren call. Love is in the water, and so are excess proteins. If the foam in the pond is a bit fishy smelling, then that is what's going on and it should be gone in a couple of days. There's no need to treat it.
There are a few potential causes of foam in your pond. The most common reason for foam in a pond this time of year is that your fish are doing the Spring thing.
Over-application of pond bacteria can create foam in the pond temporarily, in which case there would be no odor accompanying the foam and it will dissipate in a few days.
Another cause of foam in a pond could be a dead animal in the pond and you will need to locate and remove it immediately.
Soap being thrown in the water can obviously cause foam in a pond. This typically doesn't happen to backyard ponds, but if you have a front yard pond or it's in a commercial location, it's a possibility. In this case, the pond will have to be drained, cleaned, and re-started. This would also kill the fish. If this has happened to you, you have our sincere condolences. And may the bad karma of whoever did it be swift!
So, if it's just your fish being twitterpated, no worries, all will settle down again shortly. If it's something else that you need help with, don't hesitate to ask for help.