Ameca splendens is one of a family of viviparous fish known as goodeids. Goodeids (named after the ichthyologist George Brown Goode) are also known as split-fins because of the distinctive notched shape of the male’s anal fin. This has evolved into a primitive copulatory organ called an andropodium.
These fascinating fish are sometimes called true livebearers because, unlike the popular guppies and swordtails, the females nourish the young via an organ similar to the mammalian umbilical cord (the trophotaeniae). In addition, females are unable to store sperm, and must mate after giving birth to become pregnant again.
All goodeids come from central Mexico and are considered to be endangered. Some species are thought to be extinct in the wild and are maintained only in the tanks of enthusiasts. This family thus offers the aquarist an excellent opportunity to contribute to a worthy conservation effort.
A. splendens is one the most attractive members of the family and consequently it’s probably the most popular. A robust and active fish, the dominant males catch the eye when flashing their yellow tails at the females. Like most of the goodeids however, it has a deserved reputation for fin-nipping and occasionally its aggression leads to the death of weaker tank mates.
Distribution & Availability
Limited to a small area of the Ameca river basin in Mexico A. splendens is a red-listed species which, depending on which reference you use, is either extinct in the wild or critically endangered. It’s not generally offered for sale in shops but is widely available at club auctions and by mail order.
- Males – up to 7cm. Typical goodeid shape with the dorsal and anal fins positioned well to the rear of the bodies. The flanks are silvery grey and dappled with metallic scales. The caudal fin is terminated in a black, then a yellow band. Anal fin modified into an andropodium.
- Females – up to 12cm though probably smaller in most aquariums. Silver body with black spots. Has been described as being like a miniature salmon.
A boisterous fish in common with many goodeids and best kept in a species tank. Deep Sea World visitor attraction at North Queensferry in Scotland has a colony co-habiting with a large group of piranhas.
- Tank size: 90cm minimum.
- Decoration: needs a lot of room for swimming and plenty hiding places as dominant males will bully smaller individuals as well as harass females.
- Temperature: 25-28oC
- pH: 7-8
- Hardness: not too soft, 5-20odH
A. splendens is an omnivore that will eat just about anything. It thrives on a diet high in vegetable matter and will graze on algae. Use a good quality flake food and supplement with vegetables such as peas and spinach. Offer frozen or live food weekly.
Breeding A. splendens is not difficult. Kept in a colony, the females will naturally fall pregnant. Gestation is around 60 days and before giving birth the females are huge. After dropping around 10-15 fry, the females resemble a deflated balloon. The fry are large (up to 2cm) and after a day or two will be eating much the same diet as the adults. Some adults will chase and occasionally kill fry but I never witnessed one being eaten. I always removed fry to prevent any unnecessary deaths. They can be reintroduced into the colony when they are around 3cm, which they will reach in about one month. It’s an amazing sight to see such large fry. Of additional interest is the fact that they are born with their little umbilical cords still attached. These drop off within a day or so.
USA Show standards
- Size: Males 7cm, females 8.5cm
- Breeding category: D
- Show class: AO
If you have the space to keep a colony of these fascinating fish then I recommend them. Lively and attractive, they deserve more attention.
- Baensch, Fischer (1997): Aquarium Atlas Photo Index (1-5) – Amazon
- Fishbase species summary
- The IUCN Red List of threatened species