@Guide Any fish on the Noxious Aquatic Species list that you catch, you are obligated under the law not to return them to the body you took them from. Goldfish and many others are on this list.

You can't really make a goldfish specific trap, you can only kill them as you catch them. You can make traps that don't do harm to the fish they catch though, old style basket traps for example. I'll be doing plenty to cull the local goldfish and other NAS populations.

It's a good source of fertilizer and food for the animals I'll be keeping.