I have a 40 gallon tank with 3 silver dollars, an angel fish, a red tail shark, and a pleco. I plan to get a new angelfish soon. With the fish I have in the tank, would I be able to add some albino tiger barbs? I've heard that you cannot have tiger barbs with silver dollars due to their size but I've also heard that you can keep them together. I don't know how much the space in my tank would affect it.