I did put another irridescent shark,a really small one ,but he totally ignore the new one.It seems like he is trying to find his friends..)
In fact,he ignore everything,even food.
The little new one get along even better with my 2 pimelodus pictus,because my big shark is rejecting him....
The lonely one(the one who doesn't eat) turn around and constantly do that all day..
I think I am going to call the people who adopted my 2 other sharks,they whanted that one too...but I am sad to give him away...
) :
Anyway,I don't whant him to die or get depressed...
Should I do that?(Give it to my friend who adopted his two brothers)
my thank is a 20 Gallon only,and this shark is getting big(about 8 inch1/2).Is it too small for him?I really have to tale a decision soon!!
Do they grow really fast?How long should I keep him in that tank?,if I should keep him...
I need expert advice...

??I really have to take a decision soon!!Thanks again