Struggling with new tank for months

[Abigail_Irene]

Hi Everyone,
I’m new here and hope you can help! My husband and I got a brand new 20 gallon aquarium in November and started with a pleco, Cory catfish, and platy. We let it cycle for several weeks before getting more platys. Then, all the fish just started dying. We found out we had an ammonia problem probably from over feeding and that was really difficult to fix, but we got it under control. We also got another tank and moved the remaining fish over there and they’re doing great. Then, we got three goldfish and put them in the 20 gallon tank. We tested the water and all the levels looked great and still do. Now, two just died and the black moor is covered in white splotches and I have no idea what they are!! I feel like it’s somehow the tank because the other fish are happy with the same water and everything. We tested for ammonia, pH, copper, nitrates, nitrites, tons of other stuff and it all looks fine. Sorry for the long post, but does anyone know what’s going on and/or how to help my little black moor?? Thank you!!

 

[libertybelle]

Probably ich from the stress of cycling. Have you read up about cycling. Usually when people say ‘we let it cycle for a few weeks’. It means they set it up and let it sit there, not actually cycling.

What are the actual numbers on all your parameter tests.