If you could, mind telling me how big of a tank and the exact stock list? Either way, I've kept parrots and silver dollars for years, so I can give some advice.
The tank is 330 liter (87 us gallon) the tank consists of 9 parrots, 8 silver dollars, 2 of the silver fish shown below, 2 of the black fish with the red tail shown below, 5 apple snails and 3 pleco.
Informed him of the salt and heat method but he decided to go with chemical Seachem Paraguard. He doesn't have time he says.