At best - it's a reference chart....It ALL depends on the individual fish you get, and the other one you try to pair him up with. Do not expect that chart to be accurate more than 1/2 the time, as there are too many variables, such as in a 100 g tank, 2 species may not do well, but in a 500g system, it's doable. OR when mixing several species, good or bad things can happen......just cause the chart sayz it works, is dependent on ALOT of factors.