True, but fishing the farm pond for trash is just a complete waste of a day, because you don't generate anything else of value, and at only 3 XP per catch, it won't make a meaningful dent in your progression to the next level on your Fishing skill either. Even if you only want enough quality sprinklers to fit around one scarecrow, which is about 22 of them while still keeping every plot protected from crows, you'll take a long time to collect that many Joja CDs and Broken Glasses with normal fishing outside the farm.
Honestly OP, I think you're better off mining for the quartz, and smelting it, because you'll be making progress down the mines, and picking up useful and valuable items along the way. You'll quickly be swimming in quartz from the mines anyway, meaning it's not even worth the inventory space to hang on to the CDs and Glasses from fishing. And if you run low on coal, honestly, just buy it from Clint; it's only 150g each, and the activity you fit into the time saved will earn you more money than that