Hikari Usa Inc AHK73366 Pond Cyropro 16-Ounce

Q: Will this kill anchor worms that are already attached to a goldfish in an aquarium or it used just to kill larvae and prevent infestation?

When I used this in the middle of fall 2014, there were anchorworms already attached to a couple of my goldies. In a short time (cannot tell you exactly), they no longer had the worms attached. They're doing great even months later!It appears to have killed the attached worms, kill larvae, AND prevent infestation. Hope this helps your decision.

Q: How many gallons does this 16 oz. bottle treat?

Per the manufacture this product will Treats 5000 Gallons per bottle. Please let me know if you have any other questions

Q: Can I use this with scaleless fish and in a tank that has shrimp and snails?

The Hikari website says it is safe for ALL fish, reptiles, amphibians and mollusks (snails) but not safe for crustaceans (shrimp). So safe for scaleless fish and snails, but not safe for shrimp.