Betta coccina was the first fish of the B. coccina group to be discovered and a true revolution since we only knew B. splendens varieties with such a beautiful red color. Plus this species had another unique mark which will be described later.
This species habitats peat swamps that lie deep in the forests. These swamps have extreme water conditions, fish have been found in water with a pH between 4.0 - 6.0, a dH between 0.0 - 4.0 and a KH of 0.0 with the water temperature being around 70 ° to 78 °F. The reason why the temperatures are that low compared to the savannah habitats of B. smaragdina and B. splendens is because the puddles, in which Betta coccina lives are surrounded by trees that stop almost any direct sunlight resulting in shaded, cool water. The water is tea-colored as a result of leaf litter that falls in the water providing the water conditions described above. In water this soft and acidic there's not much chance for plants to survive with the exception of the few Cryptocoryne species.
These habitats are known for drying up during the dry season when there is no rain. All that's left are small puddles and wet layers of leafs both in which this species manages to survive until the next rainfall. This is characteristic for the B. coccina group.
B. coccina reaches a total length of 2.5inches, both sexes share that length although females can be a little smaller than males. The first description refers to the male. The body is sometimes slender and sometimes more B. smaragdina shaped, it depends on the individual fish. The color of the body can differ from light to dark brown but also from bright to wine-red. It's common that male shows a dark brown body with two horizontal lighter brown bars running from the eye to the start of the caudal fin. Their eyes are bright blue. The dorsal, anal, caudal and pelvic fins are bright to wine-red and in adults the dorsal and caudal fins have a white edge which is black in the anal and pelvic fins. The quills are gold to red. Both sexes possess wine-red, blackish spots in the dorsal and caudal fin that sometimes also has white spots in male specimens. The pectoral fins are transparent. The unique mark that this species and a lot of other species of the B. coccina group have is a bright blue blotch on their sides! Only young males possess such a spot and as the male grows older the blotch slowly disappears. Now and then the blotch may also chance in a blue, bar like figure. However the spot is not a rule for Betta coccina, there are a lot of recordings where the males did not have the spot and it's even been described some males have the spot on one side of their body but not on the other! Conspicuous is the fact that the lateral blotch is a spot where other B. coccina target their attack on, mostly just gentle pushes with the mouth.