I have had a killifish in my tank for a few years with other community fish and have noticed a few fish going missing including all my platies....it seems to me that this is the only fish in the tank with a mouth big enough to eat these!! Do you think its my killifish getting grumpy in it's old age?? Shall i put him in a tank on its own or would it be better with some other fish as company?? I currently have a 5 gallon tank that is running but empty except for a large group of snails (my 2 year old daughter likes them!!)