Can she afford the massive tank its going to need? A 55 or 75g or even a 100g tank is not big enough. Please do research before buying fish.........Pacus should not be kept in home aquariums....they just get too big.
And I don't recommend you buy anymore fish for your 10g. You should have stuck with the 1 Dragon Goby, nursed it back to health and upgraded the tanksize before you thought about getting another one.
And the 20g tub.....I'm sure the minnows are for the turtle, but with only 10 or so gallons of water in there now and the pleco, its already overstocked. I would not suggest adding that many minnows at one time. You are risking killing your fish.
Please, please research before buying anymore fish. Fish do not grow to the size of their tank like you may have heard. They get stunted and die.