I've had most success with wells. I've had fish continue to drop irregularly from hydronous hollow, fall pond, and swampy pond. Mermaid pond has been a lot more stingy. I've not received any from Lorelei's fountain, koi pond or blossom bridge. Pond drop is extremely poor. I'm collecting from these (9 wells, 2 hydronous hollows, fall and swampy pond) each time I log in using just 13 energy. I'm not doing too badly with doing it this way. While I'm not doing this every two hours, it could be done. My sparrow dome is level 4.