Characodon audax

Pair of Characodon audax "El Toboso" Smith & Miller, 1986

Common Name: Black Prince (for El Toboso location), Bold Characodon

Synonyms: Characodon lateralis "El Toboso"

Meaning of Name

Genus- Characodon Charax, -akos = a fish without identification + Greek, odous = teeth 
Species- audax = bold or spirited


Characodon audax "El Toboso" is a livebearing goodeid from the Pacific Coast of Mexico. The common name for this fish is the "Bold Goodeid", but within the livebearer hobby in the USA, the "El Toboso" location is often referred to as the "Black Prince" and has achieved a near cult-like status among livebearing hobbyists. Charcodon audax "El Toboso" is a striking looking fish. Males have have silvery-gold speckles on the flanks and velvety black dorsal, anal and caudal fins. Females are drab by comparison, but some exhibit some nice speckles on the flanks.

At his talk at the 2014 ALA convention on the genus Characodon, Juan Miguel Artigas Azas listed fourteen location points. Generally speaking, the conservation status of all Characodon is dire. Nine of the fourteen locations are thought to be extinct in the wild. If you get a chance to keep Charcodon from any location, you should diligently maintain each variant separately.

Why not dedicate a tank or two for species maintenance for Characodon? These fish need our help!


All of known Characodon species have been found in a geographically isolated areas of Mexico, but Chaacodon audax "El Toboso" is likely the most geographically isolated location. Indeed, only a few individuals still found in a single location near a small dam near the village of El Toboso, MX.

Typical habitats for Characodon species are clear spring-fed lakes and creeks that are shallow with the presence of abundant aquatic vegetation.

Size, Maturity, and Sexual Dimorphism

Size: Males- 1.5 inches, Females 2.0 inches
Maturity: 1.5 inch
Sexual Dimorphism: Males are more colorful. Males have an adropodium.


Characodon audax is probably not a fish for the novice livebearer keeper, but it is not too difficult to maintain once you know the tricks. Unlike other livebearers, Characodon audax "El Toboso" is territorial. Males will spar with other males, females spar amongst themselves, and the largest most dominant individual may aggressively pursue everyone else. This fish does not do well as pairs with the more aggressive individual causing great stress to the other. I recommend keeping this species in larger groups of six plus fish which helps to offset aggression by distributing it among more individuals.

Bigger tanks are a necessity for Characodon audax and ten gallon tanks are not recommended for adult fish. A twenty gallon or larger tank is required and it is best to treat this fish much like a territorial cichlid. When setting up the tank, provide piles of rocks and caves. Employ lots of floating or rooted plastic or live plants to break up the sight lines and provide safe harbor for females and less dominant individuals. 

Like most goodeids, you should keep this fish on the cool side between 68F and 74F in hard water. They do very well around room temperature of 70-72F. 


In the wild, Characodon audax are likely omnivorous. In the aquarium, they readily accept flake food. Experienced breeders of Characodon sometimes warn against feeding a high protein diet. For that reason, I would recommend offering a good quality vegetable flake. I fed mine HBH Graze and Dainichi Veggie Deluxe pellets. Occasional treats of Repashy Spawn and Grow gel food was also offered.


I obtained a dozen Characodon audax "El Toboso" fry from Shawn Erickson of Omaha, Nebraska. When I received the fish, they were about an three-quarters of an inch long. I placed them in a ten gallon tank for grow out which contained numerous plants and caves. After about ten months, the now 1.25" to 1.5" fish were starting to get chippy and I quickly moved them to a 30G sand substrate tank which was heavily landscaped with rocks and floating plastic plants. This particular tank received weekly water changes of two-thirds of the tanks volume and was unheated. Typical temperatures were 65F to 73F. Filtration was provided by a Swiss Tropicals matten filter.

When the fish started approaching two inches, I saw gravid females, but only a fry or two after birth. After doing some research, and confirmed by my later observations, I determined that Characodon audax "El Toboso" fry are barely motile during the first 12-24 months of life and sink to the bottom. In my tank, most were picked off by other adults.

The next time I observed a gravid female, I moved her to another tank and placed her in a fry trap (See Build your Own Plastic Mesh Fry Trap).

After a few days in the trap, she delivered eleven one-half inch plus long fry. As previously mentioned, the babies can't really swim right away. In the wild, I believe, females drop their fry in heavily planted areas where they seek cover.

After 24 hours, the fry began to jerkily swim around and were quite shy. I offered live baby brine shrimp and the fry were able to take them immediately and were easy to transition to flake food. The fry are rather slow growing, taking almost three months to get up to an inch.

I believe that Characodon are seasonal breeders who benefit from a cooling down and warming up period. In my experience, they will reproduce year round, but the largest fry drops occur in the first gestation after the cool down.


Characodon audax "El Toboso" is a beautiful goodeid that is critically endangered in the wild. While it is somewhat challenging compared to other livebearers, it is by no means a difficult fish if you can dedicate a larger tank. Better yet, having bred this fish, there are some "bragging rights" gained as you relate how you bred one of the more challenging species.


  • Juan Miguel Artigas Agas, Charadocon Talk, 2014 ALA Convention
  • Tobeler, Michi & N. Betrand 2014. "Morphological variation in vanishing Mexican desert fishes of the genus Chaacodon (Goodidae). Journal of Fish Biology, 283.
  • Goodeid Working Group Website, Characodon audax Species Profile