I thought I'd upload this vid as I didn't think you could do this with fish. We have a tank which has rescued British Course fish, 2 Roach and 1 Perch. The Perch is called Desperate Dave and was very sick with a bacterial infection (turned black with green eyes and barely moved), but by some miricle got better and has started eating and being active again.(think he maybe slighty blind now, keeps bumping into things and has green tint to eyes still) The new fish the Guppies were rescued from my mum's tank in which the heater had broken ages ago but the fish still survived (surprizing for tropical fish). She wanted rid of them so we offered to take them. And look now! Tropical fish and course fish thriving and breeding in the same tank. P.S We also have a crayfish in there called Mrs Pinchy (she eats the left overs)