Interpet Aquarium Anti-Crustacean Parasite No.12 100ml This 100ml will treat 250 litres (55 gallons). Large higher level parasites can be introduced into the aquarium on new fish or plants. They cause life threatening damage and should be eradicated quickly. Crustacean parasites are very difficult to eradicate, so this treatment is powerful. Therefore, take care to carefully follow all instructions and note any warnings. There is a handy pipettte and measuring cup, there is also a chart to calculate the required dosage as well as a chart to aid diagnosis of alternative fish problems. Price: £4.29 Quantity: