Too many fishes in too small a tank. Just imagine 5 people living in an apartment the size of a bedroom without toilet. Sure got problems.

Keep an extreme max of 1 gf per 1 cubic feet of water. ie ur tank size best to keep only 2 gfs. I hv 12 gfs in a 6'x3'x2' FGT.

Wat filter u using? n how much u feed? Tis will dictate how much & how often need to change water. I feed alot, i change 50% twice a week, using multiple filters.

Take good care of ur water, n the gfs will take care of themselves.

Happy rearing water