Will it eat my fish?

I have spotted this crab recently in my tank. It probably came with new live rock 2 weeks ago. Will it eat any of my fish or corals?
Should I feed it (what will it eat) or get rid of it?
I have a yellow tang, 2 common clowns, a cleaner wrasse, a leather coral, a brown star polyps and a purple tip anemone.
I have also spotted this other creature that comes out at night and cleans the algae on the glass. What is it, and is it peacefull?

 

Hello Hendrik - no the crab should not eat fish at this stage. Perhaps when it becomes bigger it might. This crab will MOST likely kill and eat some hermit crabs, snails, etc.

It is always a good idea to banish crabs like these to the sump, if you can manage to catch it. As you never know when they will start killing your life stock, and perhaps start eating your inverts.....

No - please don't try and feed this crab.

The snail is completely harmless, and a VERY good part of the cleaner crew.
The snail will constantly chow diatoms and algae on the glass of the tank. They mostly come out at night. They also breed very quickly....

 

Crabs with very pointy claws, WILL at some point attack your live stock, crabs with blunt rounded claws MAY at some point attack your livestock, but do try to remember, the crab didn't ask to be in your tank, there it was, asleep in it's little cave then it woke up in a tank, so please don't kill it or release it back into the wild, sump it and feed it, it is YOUR responsibility.
Second looks like a stomatella, good guy to have.

 

if you don't want it, i'll feed it to my mantis, plz

 

Looks quite similar to an Eriphia sp. crab I once had. He was not a very nice tankmate once he got bigger.

 

sweet!!!
post him to me

 

Fluffy (my first O.s.) was hungry.

 

nice:1biggrin:

 

If you really want it, I will first have to catch it.

 

that will be awesome hendrik really awesome.
will you do that for me?

 

Put some meaty food in the bottom of a smooth glass. Lean that glass against the rock you think the crab is living in. They get attracted to the smell, investigate, and fall in. Then they can't get enought traction to climb back out. However, don't be shocked it you find your favorite hermit crabs in there too.