Is there an effective treatment for aquarium fish lice in the uk where organophosphates are banned?
Without organophosphates it’s not going to be easy as that class of chemical is the backbone of most treatments available in the US such as Clout. You might speak with a veterinarian in your area and explain the problem and ask for potential medication solutions. Copper based medications can be used, but to limited success as to kill the adult lice the dosage would kill the host fish as well. Copper will however kill other life stages of the lice in your tank. You could then deal with the adults by using a 3% salt dip for 1 minute. That will kill the adults that are on the fish while the copper kills other stages in the tank. It would take some time and at least one dip a day for each infected fish for as long as 10 days or possibly more, but after 2 weeks of the duel treatment you should be able to eliminate the lice.
