The point is not how healthy, or how big your lung fish is.
The point, in reality is; goldfish are not an ideal staple, nor are they nutritious, and they carry many parasites as any body here will tell you. Just not good practice, once again.
Fish also need a varied diet, anyway.
Your fish is nice, has some size to it, but there are quite a few of us with lungfish like that, size wise, and color wise. It being huge and white does not mean it is an exception, and can be fed solely a cloud of goldfish.
And, you missed my whole point about the cloud of goldfish. That group of goldfish is producing a lot of wastes that is ALSO unhealthy for the lungfish,
and to be quite blunt, your water looks like S---T.
We are just giving you wise, experienced advice that could help you and your fish have a much more enjoyable, and even more healthy life.