Questions - Need some input

The store sold it to me as a black percula... but it only cost $20 and black percs are ususally upwards of $70

I had my nitrates spike and most of my fish die a few weeks ago. I've been doing water changes nearly every other day with RODI water and am now starting to introduce some heartier fish like clowns. This I want to pair this gal up with a smaller clown so that it will become the larger female... but I don't know if I can safely put it with a regular orange/white percula...? ...

Hey all, I am new to this whole site- but am looking for some helpp.

I woke up this morning to find that my new emerald crab had eaten a $30 coral frag- so I traded him at my LFS for a couple more snails.

I tossed the bag in the tank to acclimate and noticed I had a little hitchhiker- before adding him to my tank, I'd like to figure out what it is make sure it isn't a toxic nutibranch that is gonna kill everything or something like that.

He is white/clear- ...