So, when scaling a fish, there's a couple different ways to do this. They do have tools for it. When you buy a fish, try and have your fishmonger or the sales person to actually scale it for you, because it can get pretty messy.
So, unless you have a backyard or a nice big sink to do it in, just be leary of this process. Some people like to use a box grater, like a cheese grater. Not my favorite, but it's doable.
The other thing to do is just use the back of the knife. And what you want to do is just kind of go against the scales. So, coming up from the bottom to the top. And what you'll end up seeing is that a lot of those scales will come right off.
If you eat skin, if you like the skin on your fish, whether it's salmon or striper, or snapper, then you really want to do this process. If you don't really like the skin and you're going to take it off anyway, it's not totally necessary, all though it will make your filleting and breaking down the fish a lot easier. So, just be careful, because these tend to go everywhere when you start doing it. So, really make sure that you have a good place to do it in or put down some plastic like garbage bags and stuff so that you can catch a lot of it.