I noticed my African knife monday after I came home from school band practice to find him that he has some white markings on them. There really small . Kinda looks like its skin is peeling. I think it is ihc or ick so I added some Quick Cure for Ick in the tank and used a lil bit more then half strength since its a scaleless fish. Is it the right thing to do . I think its pretty bad and it seems its been there for some days now. I heard of quarantining the fish but I dont have an extra tank but I have a bucket which is I think bigger then 5G. What do I do? Will it be too late? Reply Asap. I know I m not a good fish keeper. I just don't want my Knife to go byby 
*Forgot to add that it is in a 55G with 3 Rainbowfish and a senegal Bichir

*Forgot to add that it is in a 55G with 3 Rainbowfish and a senegal Bichir