• Scientific name: Characodon audax
• Synonyms: -
• Common name: Bold characodon
• Group: Livebearers
• Habitat: Central America; Mexico
• Size: 5 cm
• Biotope: Found along the upper part of the Río Mezquital, in small ponds and in shallow streams.
• Social behavior: Males are quite aggressive with each other, and may harras the females constantly, so they are best kept in a species tank.
• Diet: Omnivorous; In nature they feed on Daphnia or other small invertebrates, and they also eat green filamentous algae. They will accept most foods in the aquarium, but they also need some vegetable matter, such as algae.
• Breeding: Quite easy
• Tank: Minimum 50 litres
• Population: 1 male and 2-3 females for 75 litres
• Decoration: Needs a tank with dense vegetation with dark substrate and some tree branches or roots. It is important to have enough hiding areas for the females. Water movement shouldn’t be strong.
• Temperature: 20-24 °C
• pH: 7-8
• Hardness: 6-20 NK°
• Lifespan: 3-5 years

Description: Characodon audax have different color-variants. The body color of the males can vary from olive-gray to light brown, depending on the origin. Some fish have silvery scales on their sides, mostly the specimens from El Toboso. The back, and the upper parts of the head, and the lower body of adult males from this region are dark gray or black. Their sides are also dark, but because of the silvery scales this region has a reticulated pattern. Most of their fins are also black. Fish from different locations have reddish or yellow fins sometimes with broad black margins. The color variant from Los Pinos have a reddish body color from the beginning of the dorsal fin to the caudal fin, while the underside of the head and the breast are yellowish or deep orange. The sides, the top of the head, and the back of adult females are brownish or green, while in some color variants these are light brown. There is a greenish-blue wedge shaped region between the pelvic fin and the anal fin, while the belly is bluish gray. There are a midlateral series of irregular blotches on their body, which is sometimes form a solid midlateral stripe. Characodon audax is listed as Vulnerable on the IUCN Red List of Threatened species.

Under the right conditions their breeding isn’t quite hard. The most important is the cooler water temperature, so ensure that their water temp does not goes above 24 °C for a long period. After about 60 days of gestation period, the females will give birth to 5-10 fry. The fry should be raised in a separate tank.