Let me help out a bit here. For those more accustomed to tanks in gallons, as I am, we are taking about a simple 20 gallon tank here. I count the apple snails as 3 gallons each, the pleco is probably in excess of 3 gallons by itself, the DGs are each at least 2 gallons each. As such I arrive at around 14 gallons of current stock levels. I have no idea what a harlequin dart may be so I have no equivalent for that. Let us guess that they are only tiny and amount to only an inch equivalent each, so we are at 24 gallons of stocking. With a 20 gallon tank, let's call it 20 x 3.79 or about 75 litres. The loaches look to be a bit of overstock to me. If you are willing to sacrifice your snails for the loaches, things will work out. Either way, you are at about all that your tank can readily sustain in terms of stocking levels.
