I'm glad I could help you feel better about using it - despite my lack of catfish knowledge. I really hope it helps him. . . and aren't those pretty little Pearlies Ramshorns? I don't think ANYTHING
can kill Ramshorns - unless you REALLY want them dead! You could always pull a handfull of 'em out and pop 'em in a jar just to have a backup. . . I've had a few Ramshorns that rode in on plants living in a jar with a bit of sand, a nano marimo ball, and some duckweed for MONTHS, lol! They're just sitting on my desk, being snails . . . don't seem to mind much of anything! Just hope it works on that adorably beady little eye! C'MON, SPARKY! FIGHT!