Yes it's all copper. it's enclosed with the stock cover. You can kind of see the clear plastic in some of the pics. But I had not actually thought about it poisoning the fish. I guess it would be possible if there was evaporation and then it dripped back into the tank. Luckily I had a cover. I would have probably still used copper even if I did not have a cover.
Yes i just saw the cover. Probably it will not be any problem. As you say evaporation and dripping back to water is also posinious, but take a look to the link below. Obviously powdery oxidations dropped on water. I just wanted to let you know. Ne need to misunderstanding
Forum is all Turkish but you can check the photos, even very thin led stripes copper lines can get oxidate that much... Without cover
, your heatsink can be worst.
Happy days and fishes...