Redwood Rhiadra

Technically, Maitimo made a mistake, since you don't put custom catches in the server barrel itself. There's a separate object called a Custom Prize Giver (CPG) into which you can put items, and these will be given out according to the rules set in the CPG's configuration notecards - they can be given as a percentage of all catches, or assigned rarities and given out as a percentage of that kind of catch. You still get the official fish as well, the CPG works in addition to. You can even see a list of fishing areas with customs on the 7Seas website: http://www.7seasfishing.com/areas.html (select "Areas with Customs") The CPG is part of the Fishing Area Kit (i.e. it comes with the server) and is fully documented there. It doesn't come with the rods (and isnt' documented with them).

This isn't a gacha. A "machine" in which you choose which item you get for a particular price is just a standard vendor.