this is a harmless mould, i have it in my tank and i have forgetten its name, does it move like coral if so then it is the same, one that i have and the only fish species to help get rid of it without using a chemical
is the Siamese flying fox, they have control mine, the plecos dont like it

hope this helps, if i can see some i will get a pic for you

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i have 2 community tanks
and i breed angels and bristle noses

i love my fishies