I have a mate with a quite big black ghost knife fish and he is moving so he wants me to take care of it in my tank for 2 weeks but it is aggressive and will attack my favorite guppies and Pecos i have another tank but it is not big enough to hold the BGKF or my other fish what should i do and is there a Quick cheap solution because my mate has no one else to leave it with and i dont want him to have to sell it Help please