When I changed my res a couple of days ago, I noticed a little dead bug floating in the water, scooped it out and I reckon it was a silverfish. I just noticed another 1 floating in my nutrient mixing tank.

Are silverfish harmful to plants?

Thanks Lucas, very informative..... Just can't understand why I'm getting them, my room is spotless and I always clean any spills immediately. My temps and humidity are good too. Gonna check the room thoroughly though, just to make sure.
Again many thanks.