Yah, this is the depressing part about sacred clay items.
When the game first came out, I was right on board to get the new items. They only gave like 10-15% more xp when being used, but they lasted for days. After numerous updates, the items now give 2x xp when being used, but disappear in hours.
Personally, I haven't wasted my time on the game since the latest update because I used to get like 150k points a game. Of course, items then costed 20k points, but I was able to get like 5-6 items with only 1 game.
As for botting, I don't bot a ton anymore and most of the bots I have are super old and run on color information that is non-existant in the game now
:-s. I would suggest just searching for one, or asking someone who knows about fishing bots.(obviously)
* I also wouldn't suggest using these items for botting. Since they disappear, they are going to be pretty useless in a bot. You could just have a cut off for the bot, or another harpoon in your inv for the time that it will crumble. This could be a bit complex and using a normal harpoon while botting is advised.