When Will It Overload The Filter --- Is My Tank Over Stocked

[samxx]

i have in my 23 gallon uk tank
1x male guppy
1x 4 month old male guppy
5 x 4 month old female guppies
5 x female guppies
4 x 1 month old guppies
3 x scissors tips
1x common plec ( which i will be selling soon )
is that over stocked
is my filter going to over loaded

 

[love cichlids]

if you have a filter that will be good for a 40 gallon tank and do 2 water changes a week of at least 20% you should be ok, i think. Someone else might think different.