"That fish practices eating."
Translation:Con cá đó tập ăn.
The tips section for demonstrative determiners agrees with JCMcGee:
"Đó/Kia is equivalent to that or those. They are also placed after noun(s). Example: con gà đó (that chicken), nhà ga đó (that train station). Đó and kia are interchangable."
"Important: For the rest of the skill tree, the word kia will NOT appear frequently. Most commonly used demonstratives are đây, đó, and này so you are recommended to use these words if you encounter sentences with demonstratives."
"Important: Technically, đây and này are the same. They are both equivalent to English "this/these" and they both can be used as adjective for a noun or as an independent subject. However, for the sake of this course, đây will NOT be used as adjective and này will NOT be used as independent subject."
Of course they are interchangeable, if used alone, because they both express distance from a subject/object. But this was not the question. The question was about the difference between them and Familiarguy is right. They are different, like the demonstrative determiner in some roman languages. This is important to know if you use them together in a sentence: the one is far from you (dó) and the other even more (kia). This is also why it qualifies the subject/object (how far).
Because the slang part comes always after learning the basics of a new language. At the beginning it is very important to stick to grammar to learn properly. But if you think, a possible correct answer is missing, feel free to report it using the flag, maybe they will add it!