If the angels are tank bred, which most are these days, then they will be used to living in tapwater and will not be as fussy about water conditions, i have had a pair spawn in water with a pH of 8.5! If they are wild caught they will need a pH of around 6.5 but since wild caught angels are rare and would cost a fortune i dont think you need to worry about it.
Angelfish should grow to between 8 and 12 inches from fin tip to fin tip and fully grown fish that have not been stunted will need a tank with a minimum 36" length and 18" height with a 20" height being prefferable.
A 10g tank is not big enough to house angelfish as a properly grown adults dorsal fin will be as high as the water level. As for saying a fish is happy think of it this way, you can keep a dog in 6ft by 6ft shed for the whole of its life and it will still wag its tail and be excited to see you when you come to feed it and clean the shed out, but it is not right and the dog would be taken away from you if the authorities found out, fish deserve to be treated with kindness and respect too.
And for the record platys do not grow to 6", the fish you saw were probably mollies as platys rarely exceed 3".
Angelfish should grow to between 8 and 12 inches from fin tip to fin tip and fully grown fish that have not been stunted will need a tank with a minimum 36" length and 18" height with a 20" height being prefferable.
A 10g tank is not big enough to house angelfish as a properly grown adults dorsal fin will be as high as the water level. As for saying a fish is happy think of it this way, you can keep a dog in 6ft by 6ft shed for the whole of its life and it will still wag its tail and be excited to see you when you come to feed it and clean the shed out, but it is not right and the dog would be taken away from you if the authorities found out, fish deserve to be treated with kindness and respect too.
And for the record platys do not grow to 6", the fish you saw were probably mollies as platys rarely exceed 3".