very sad about little Fury

[dillia31]

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