i have a 380 litre tank with 2 male yellow top mbamba and 5 females and 5 electric yellows i cant tell what sex they are , *** had these in my tank for about 2.5 years my biggest fish is like 2.5 inches i feed them twice a day i use hikari fish food over these 2.5 my fish have only grown like 1cm each i dont know whats going on? can anyone help me?