Hello everyone, I am currently obsessed with fishlore and am constantly on here reading random posts, some of which get me to wonder the how's, What's, and why's of the aquarium worlds. I'm a curious bug and would greatly appreciate any answers. Thanks in advanced!! 1. Hydra - is it an algae? Or a creature? I researched and I guess it's related to jellyfish? - I see posts about a hydra spotting and the tank owner flips out and destroys the tank setup trying to get rid of it. Is hydra dangerous for fish? I personally think it's cute from pictures I've seen.. o.o 2. Decorations - I see alot of rocks and driftwood in tanks. How do you know a rock or something in/on the driftwood won't alter the water chemistry in a bad way. Like can't a rock add iron/copper/lead etc.? - is it okay to just reach your hand into a tank to add/move/remove a decoration? Should you wash your hands first? Should you use special soap? Or like rise with vinager water or something? 3. Water - I see everyone using tap water and then having to use ALL these chemicals to counteract the chlorine, chlormamine, and trace metals. I feel like im the only one who uses bottled distilled water. Why? - the only down side I've found using bottled water is a low pH. What pH do fish like to be at? I have giant danios and plecos. 4. Do fish get bored? I saw a Betts mirror toy and the pet store yesterday and was wondering if other fish would like a mirror and if there were other fish toys? I've heard of goldfish obstical courses, but that's it. What are they anyways? Thanks again for your help and advise!! You're great for reading this far!!