- Scientific name: Hyphessobrycon eques
- Synonyms: Hyphessobrycon callistus
- Common name: Serpae Tetra, Jewel Tetra, Callistus Tetra, Blood Characin.
- Group: Characins
- Habitat: South America; From the Southern Amazon Basin to the Paraguay River Basin
- Size: 4-4,5 cm
- Biotope: Calm blackwater with little current, often full of vegetation
- Social behavior: Usually a good community fish. Keep in groups of six or more fish. Individuals behave towards each other much like Piranhas, as weaker fish are bitten and attacked, although they are not usually killed. This aggressive behavior can usually be attributed to a lack of food.
- Diet: Flake, live, insect larvae, Brine Shrimp, Tubifex.
- Breeding: Quite easy.
- Tank: Minimum 70 litres
- Population: 5-6 fish for 80 litres
- Decoration: The tank should be arranged in dark colors, and a cover of floating plants should be used to diffuse the light. Have well-planted areas for hiding, but leave open swimming areas.
- Temperature: 24-28°C
- pH: 5,5-7,5
- Hardness: 3-12 NK°
- Lifespan: 5 years
Description: Being one of the "Blood Tetras" the base body color is brilliant red to reddish brown. A black comma shaped spot is located just behind the gill cover. In some bright fish this spot may be small or not even there, in all fish it will lessen in size as the fish ages. The dorsal fin is tall and colored black with white fringe, it may have a reddish hue to it. The tail, anal, and ventral fins are red. The anal fin is fringed in black and white layers.
The tank should be well planted either using live or plastic plants and be dimmed with some floating material. As with all fish good filtration and water purity must be maintained. Feeding is not a problem as they will except all types of food, flake frozen or live, what is important is that you vary the food on a regular basis and provide enough to satisfy them. They are generally peaceful, but when there in a large school during feeding, they bite each other's fins in a feeding frenzy, reminiscent of the piranha.
The Blood Characins are some of the easier Tetras to breed. Condition the pair well and use a small breeding tank (3 to 5 gallons) with a dark substrate and containing many fine leafed plants such as Myriophyllum, Cabomba and some Java moss, also include some floating material as well. The water qualities should be soft and acidic, readings of: pH 6-7 and 4-8 dH should be fine keep the temperature in the middle seventies. The small transparent eggs will be strewn among the plants. Remove the parents after spawning. The fry hatch in 24-28 hours. Feed the young baby brine shrimp, Infusoria, egg yolk, and when larger, finely crushed flake food.