Actinopterygii (/ˌæktɪnɒptəˈrɪdʒiaɪ/; from Ancient Greek ἀκτίς (aktis) ‘having rays’ and πτέρυξ (ptérux) ‘wing, fins’), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia, as opposed to the bulkier, fleshy lobed fins of the sister clade Sarcopterygii (lobe-finned fish).

These are collectively known as labyrinth fish, they are an order of air-breathing freshwater ray-finned fish with three suborders, eight families, and at least 350 species.

Gouramis, or gouramies /ɡʊˈrɑːmi/, are a group of freshwater anabantiform fish that comprise the family Osphronemidae. The fish are native to Asia—from the Indian Subcontinent to Southeast Asia and northeasterly towards Korea. The name “gourami”, of Indonesian origin from Sundanese word the name “gurame”, is also used for fish of the families Helostomatidae and Anabantidae.

The Macropodusinae are a subfamily of freshwater anabantiform fishes in the gourami family Osphronemidae, which includes the paradisefish, fighting fish and licorice gouramis. Like all members of the family, these are air breathing fishes that frequently inhabit oxygen poor environments hostile to other fishes

The bettas exhibit two kinds of spawning behaviour: some build bubble nests, such as B. splendens, while others are mouthbrooders, such as B. picta. The mouthbrooding species are sometimes called “pseudo bettas”, and are sometimes speculated to have evolved from the nest-builders in an adaptation to their fast-moving stream habitats.