mmm a picture of the setup might help. By putting the crabs in the back i meant if you had a separate compartment in the back of the tank...bringing them to the LFS
is fine too though. Definitely post pics if you catch any
If the mandarin ate copepods then the previous owner was probably buying them and adding some to the tank since mandarins eat a lot, do you see any bugs in your refugium? Mandarins usually need a larger tank since they eat so much. I have one in my 28 nano but she eats frozen foods very well and i also have a lot of amphipods in my tank. Did you notice that your mandarin looked skinny at all? Also brine shrimp is not very good for your fish, it is more of a treat. I would look into buying some mysis shrimp and blood worms, both come in the frozen cubes.
I hope you find bernard..mandarins are great fish, specially when they are eating frozen foods haha