last night i went to go feed my fire eel and tiger oscar and i noticed my fire eel acting strange and not coming out for food which was strange because he was always the 1st one out begging at the top of the tank for food...i took a closer look and he seem rigid and had a slight glazing of the eyes but once i got close to him he swam away just fine...this morning he was on the bottom of the tank upside down only breathing and not moving..he had very glzed eyes and white bloches all over him but the were part of his color almost not a white cottton like fungus.,,,can anybody help...water parameters... ammonia=0 nitrite=0 nitrate=abt 20 ph=7.8.........75gal tank fully cycled,sand bottom lots of hiding spots for an eel........eel is abt 9 inchs oscar is abt 3