Odd one Rob,as your first batch were fine I doubt it is genetic,more likley causes are a defficiany in their diet,or an infection,I would try a dip in FMG or the interpet finrot has worked for me,can you get the Stenker beefheart in my opinion its the best food for young fish.Rearing deformed fish is pointless as nobody will want them and they rarely do very well,culling is something that all Discus breeders must do as the strains usually throw a large amount of poor youngsters,which are practically impossible to sell or even give away,a lot of people think there is money to be made in breeding but in fact you just about break even if you work out the cost and labour involved,chin up fella if Discus were easy there would be no point in keeping them lol.