Small specimen of fish so would be inch per gallon rule and depending on specimen they can range from 1.5-3"
The tank is 35L so that would mean the tank is just shy of 10gals so you would be looking at anywhere from 3-6 in that tank
just remember the inch per gallon rule applies to the fish but remember its for adult size fish not baby .5" fish and don't forget you have top middle and bottom of tank. You can get away with over stocking a tank that size if you keep really good filtration and gl with your tank setup