had no restriction to their development into adults between 4 7 weeks after treatment confirming that an effective amount of the active ingredients was no longer present in the fish fig2 and 24 represent the numbers and fecundity of female lice 3 weeks after lice challenge and 7 weeks after treatment with the exception of one of the test tanks there was no difference either in numbers of adult females or in their fecundity the treatment with neemazal u00ae comprising fish feed was very effective at reducing numbers of attached chalimi by over 90 treatment was effective at reducing numbers of pre adults to a lesser extent with females being more affected than males 17 of pre adult male reduction and 76 of pre adult female reduction the treatment had a small effect on the numbers of adult lice the females being slightly reduced and the number of males being similar in treated and untreated groups the treatment effectively eliminated egg production in gravid females the treatment prevented egg production in developing lice that survived the treatment two tanks of thirty five atlantic salmon were experimentally infected with sea lice which were then allowed to develop to the motile adult male and gravid adult female stages fish in one tank were treated by voluntary feeding using medicated feed.