I want to add new fish to the fish tank. Give me some advice.

You should supplement the situation of your fish tank (what fish do you have; The surface area of water in the fish tank, etc. ), how about your skills and so on.

Peacock fish, characteristics: easy to raise, easy to breed, good at swimming in the middle and upper reaches, small size.

Betta, resistant to hypoxia (dislike), beautiful.

Arowana, big, expensive, fashionable, novice, forget it.