When you have a large amount of bristle worms it means you are over feeding your tank
Despite their looks bristle worms are very beneficial to your tank they are completely harmless to your tank as almost all species have mouths that cannot bite living tissue as they have a mouth with no teeth or jaw as it is just like watching grandpa gumming his toast to death that is all they can do. They eat only detritus, dead flesh and tissue and left over food that's it
Once in your tank they are virtually impossible to get rid of as they can hide deep in the rocks, piping and crevices all you can hope to do is control their populations by less feeding mostly as predators that eat them tend to be picky and will usually eat them if no other food is available
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