regarding the fish...chances are no...even if they do...they would rather go for your food...so u have to strave them so as to make then go for other food...but like i said...chances are they dont...and also from my knowledge...i dont remember any nudi eating fish...
as i said before...to wait for a fish ( if there is ) to finish the zoos....by then your colony is gone...they eat 10..full liao...2 days later then eat another 10 ..then 2 days later another 10..like that dunno what how long...worst with soooo many nudis
best u do it yourself, pick out those u can...then do a freshwater dip...with the sudden change in salinity...water will move into their body via osmosis and they will die....dip no longer then 5 minutes...put back into the tank...wait for some time...the longer the better...but at least more then an hour lar...then dip again...
do it maybe 1 or 2 more times so as not to stress the zoos too much...there maybe some nudi eggs left...the eggs cannot be destroyed via freshwater dip....so after a few days, dip again to kill all the newly born nudis...continue this way for sometime...shld be able to clear off most