A big spot on my puffer (and it's not a spotted puffer!)

[jassz]

I don't get it... if the algae takes nitrate and phosphate out of the water, shouldn't I leave it? That's a good thing, isn't it?

Just this week I have started to see a bit on the rocks too. I've had some issues with 'bald rocks' on one side of the tank, so I thought it might be a good thing, but I don't actually like the look of it there. And it's spreading so fast. I had some trouble with ick some time back (and no luck quarantining) so I treated the whole tank. I was told nothing would grow again, but it's not entirely true. I do get growth on one side of the tank, like the red stuff you can see in the first picture as well as some green. It seems to grow and die a lot, but there's always some there. But the other side of the tank... not so much. Do you think it would help to change the rocks?

What about the anemone? It's not that clear, but here is a picture of one of hte big ones. Is it a bad thing?? For the fish I mean?