Is this good for a 10 gal tank?

Hi, I have a ten gal tank with 3 koi swordtails (2 female, 1 male) and a mystery snail. Is this too much for this tank?? Also I might be getting a 5ft tank for christmas. What would do good in there?? I was thinking a few a clown loachs, sparkling gauramis and a few tetra??