rabbut
I don't bite, all that often...
OK, you seriously need to get rid of some fish 
 in a 68l, to keep water changes manageable, you want a maximum of 4-5 fish... You have 19. A fully stocked 68l tank would have about 15 fish of that size, but just 8 or so for the first 6 months... You have 13 fish that are inappropriate for such a new tank if you choose to follow the fish-in cycle route, so I'd put them top of the list to get shifted. The tank is overstocked ATM and un-cycled, if you don't take them back to the store, they will almost definitely die. You kind of have the worst case scenario ATM, and continuing with the current stock would likely make you require nearer the 90% twice a day water change mark 
 With tank's this small, really, the best way to cycle is to go fishless, as the small volume of water makes for a big toxin build-up quickly, even with a light stocking 
All the best
rabbut
				
			
 in a 68l, to keep water changes manageable, you want a maximum of 4-5 fish... You have 19. A fully stocked 68l tank would have about 15 fish of that size, but just 8 or so for the first 6 months... You have 13 fish that are inappropriate for such a new tank if you choose to follow the fish-in cycle route, so I'd put them top of the list to get shifted. The tank is overstocked ATM and un-cycled, if you don't take them back to the store, they will almost definitely die. You kind of have the worst case scenario ATM, and continuing with the current stock would likely make you require nearer the 90% twice a day water change mark 
 With tank's this small, really, the best way to cycle is to go fishless, as the small volume of water makes for a big toxin build-up quickly, even with a light stocking 
All the best
rabbut
	            
 