I have recently purchased a juwel trigon 190litre aquarium to which i have added two silver sharks currently 10cm long and two angel fish ( one is black and silver and the other is brown) The fish all came from the same tank when i bought them and they seem to quite happy together in their new surroundings. I wish to add more fish but really need some advice as to which ones, I would ideally like to buy two more angels. I have also read that one shouldn't buy fish that are similar in colour and also that more aggressive fish should be added at a later stage........have i made a mistake in adding the angels and sharks first ?