Deformed Fish And Slimey Tank?

[lotlot]

Over the last few weeks i have noticed a slime overing the surface of the tank, much like what oil looks like on water. Recently a have had a number of fish that have become deformed and strange looking and died shortly after. It's really weird and i have no idea what is wrong. When the fish become deformed they seem to go really skinny behind their fins and their tail seems to go down at an angle and look totally different to usual. Any ideas?

 

[indigoj]

Lots of water changes and what are your water stats (ammonia, nitrite and nitrate)

 

[WILDER]

Run some kitchen paper at the top of the tank that will remove the grease.
Deformed fish and being skinny, fish tb to internal parasites.
So some of the fish died of bent spines and being skinny.
Can you see any fish with worms prutruding from the anus.
Any fish with long stringy white poo.
Is the anus red and inflamed or enlarged.
What type of fish have died due to the bent spines and being skinny.