No, I don't suggest doing that. That gold will reach 4 - 6 inches, and the platinums get almost as large, at least 4 inches. Thats does not fit within the "inch per gallon" rule, but either way, think about it...thats three very large fish trying to find swimming room. Also, if they are males, which i assume they are, they will wreak havoc on each other in such cramped quarters. Gouramis are VERY territorial...