Betta apollon

In adult males, the last branchiostegal ray of the gill membrane is unusually extended, with a white, laterally flattened tip.

In adult males, the last branchiostegal ray of the gill membrane is unusually extended, with a white, laterally flattened tip. A black lower-jaw band, a second stripe behind the eye and a crossbarred tail are present.

Adult length

Up to 5.2 cm (standard length, without the tail fin)

Water temperature

24–26 °C

Natural habitat

Inhabits shaded hill streams, mostly in shallow margins among roots, plants and leaves, with records also from faster water between boulders.

The extended branchiostegal ray is a fine feature that may be unclear in ordinary side-view photographs. Brown body color alone does not identify it.