When writing and practicing calligraphy you can almost use any kinds of ink. There are so many options out there which are cheap but according to my experiences I do not recommend working with a fountain pen ink, the reason being, The fountain pen ink, unlike other inks, runs. They are light and does not hold the paper much. The colors changes once dried and also they lack texture and saturation.
You can work with the Sumi Inks or drawing Inks if you can acrylic inks are the best but the tend to be on the expensive side.
I have collated ink that I really liked working with you can see the list below: