Guppymonkey.... fry will start showing color,grow faster show their gender a bit faster with optimun conditions like having a nice worm temp.80's is fine.daily,yes daily water changes about 10%.and definately a balanced diet.meaning live or frozen baby brine shrimp,daphnia and others,flakes,and also algae from the fish tank.Variety is key here.and feed them as often as possible in little portions (thats why is important to do water changes on a daily basis)
When people say they can tell their gender and start seeing colors in less than two months,is because they are doing what I described before.Now,I am not telling you are doing something wrong,as a matter of fact a friend of mine is a breeder and his one month old are twice the size and more developed than mine.Dont worryabout colors and being able to tell gender,the gonopodions will eventually appear.