Worms them and kills air sac mites in one dose 5 ml per litre
You can get it from the vet on welshpool road opposite the bird fish place in welshpool
Message me if you want I may be able to help you

I have treated mine in breeding season with this and I have no probs at all
In fact I have had over 40 young this year so far from 5 pairs... so it does not worry them
From memory its about $32 for about 150ml
Aaron