I was sooooo happy that I got a little dwarf Lion fishy,  

but sadly today wednesday I  woke up to find him dead 
 
 
 , everyone else swiming and doing thier fishy thing, three clown fishes, two small lye tail damsels,two little cleaner gobbies   the other new fish that I got with him a Nudibranch my son call  Spots  is ok
I had my little lion fish for 5 days, when I got him, he wasnt  swimming that much, and just settled at the bottom of the tank  and barley moved and did not eat very much i thought that he was just  getting use to the tank and tank mates, before we got the lion fish  my  18yr old daughter  used 1.50g of water for her 2.5 nano tank, her little   baby clown fish is doing great that she has in it, with the water she used from my tanks.  
all other fish in my tanks are doing good.
not sure what could have caused his death
the tank he came from had two  lion fish in it
 and the other lion fish is still alive
thanks
soooo sad 
