Diatoms ?

[d_b]

Can diatoms (algae) kill fish ? What exactually causes this stuff ?

[wetmanNY]

Harmless diatoms are discussed (with some links) at www.skepticalaquarist.com in the "Algae" folder-- though they're not actually algae.

[PredatorFish]

I don't know if diatoms can kill angels but diatoms are a unicellular algea that have glassy cell walls containing silica. Fossilized diatoms form sediments called diatomaceous earth.

[d_b]

Can this make your fish look like they have glossy eyes ?

[Fishiebusiness]

I don't think diatoms can directly cause any illness in fish. They may be a symptom of inbalances in your tank, which may be causing illness.

[Rocketman]

Pop-Eye Syndrome can make your fishes eyes seem glossy - untill they pop out, that is. Likely to occur in Irridescent Sharks and Oscars, although I dont see any connection between the two species.