Hi, I am new to fish keeping and would like some advice on what fish to add to my tank. I don't want it to get too crowded. I have a 75 gallon freshwater tank with an Eheim pro 3 2075 filter. I currently have 3 apple snails, 1 moonlight gourami, 1 gold gourami, 4 silver dollars, and 2 pictus catfish, all are about 2.5 inches right now. I am wondering if I have room for more fish? I would like to get 2 Discus and maybe a few green tiger barbs. Would this be too many fish? Any advice is much appreciated! Thanks!