paradise fish (English)

Japanese: paradise fish（英語表記）paradisefish

...The Thai betta ( Betta splendens ) (illustration) is a typical example, but some closely related species are also highly combative. Other species in this category include the Asian goldfish (Macropodus opercularis) and the Korean crucian carp (M. chinensis) (illustration), and are known as paradise fish in English. They were one of the earliest ornamental fish introduced from Asia to Europe, and were apparently highly regarded for their beauty.

From [Tropical Fish]

...The meaning of the habit of kissing one another is said to be a kind of combative behavior to protect territory, but it is not well understood. (d) Paradise fish Macropodus opercularis Native to southern China and the Indochina Peninsula. Total length 10 cm. ...

*Some of the terminology that mentions "paradise fish" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…タイ原産のベタBetta splendens（イラスト）が代表的だが，近縁種にも闘争性の強いものがある。トウギョ属のタイクンキンギョMacropodus opercularis，チョウセンブナM.chinensis（イラスト）などがその仲間で，英名をparadise fishという。アジアからヨーロッパにもっとも早く入った観賞魚の一つで，たいへん美しいと評価されたらしい。…