The biological family Cichlidaea is one of the most fascinating examples of animal evolution on Earth. Convict cichlids are a widespread, well-known species within this unique group.
Convict cichlids are both popular aquarium pets and fascinating scientific research subjects. In some parts of the world — like the U.S. — they’re also a problematic invasive species. Do your research before you decide to bring one home.
What Is a Convict Cichlid?
The scientific name for convict cichlids is Cichlasoma nigrofasciatus. You may also see it written as Amatitlania nigrofasciatus, an alternate name for the genus. They go by several other common names too — like zebra cichlids and zebra chanchitos.
Convict cichlids are only one example of the many thousands of species of cichlids. Scientists struggle to estimate the exact number of genera and species in the Cichlidaea family. People discover new ones all the time, while others go extinct before anyone can identify them.
Convict cichlids have a distinct look and unique behaviors compared to other cichlid species. They’re very easy to grow, breed, and maintain in an aquarium. These factors are some of the main reasons that they’re popular both as pets and for use in scientific research. These fish have been popular in the aquarium trade since the 1930s. They’ve been the subject of scientific studies — both in laboratories and their native environment — for decades.
The Convict Cichlid Habitat
Each cichlid species is typically found in a very small area. This is usually just one lake or river. They’re all freshwater species but some also do well in brackish areas. You can find cichlids in habitats like these in a handful of regions around the world, including:
- South America
- Central America
- Africa — the region with the greatest species diversity even though cichlids only live in a handful of isolated lakes
- Sri Lanka
The convict cichlid has a wider range than most cichlid species. Their natural habitat includes waterways along both coasts of Central America — from Guatemala to Honduras and El Salvador. This makes them a tropical cichlid species.
These fish live in rivers, creeks, and lakes. They prefer warm, rocky areas that provide a lot of places to hide.
Human activities have introduced this species to Australia, Japan, the rest of Central America, and much of the U.S., including:
In some areas, these fish are considered a threat to native species. They may outcompete native fish for resources and upset the balance of local ecosystems. Luckily, they seem to be isolated to small, warm portions of most U.S. waterways.
The aquarium trade is the main reason that these fish are distributed throughout the world. Based on their U.S. distribution, it’s safe to say that more than one pet owner has prematurely flushed a convict cichlid down the drain.
Physical Characteristics of Convict Cichlids
Two main physical features distinguish cichlids from other types of fish. First, all cichlids only have one nostril opening on each side of their head — not the two holes that similar fish possess. Second, the line that runs along the length of their torso, called the lateral line, is broken into two parts. Comparable non-cichlid species have one continuous lateral line.
On top of these distinguishing characteristics, all cichlid species have a core set of physical features. This includes their:
- Fin positions
- Scale composition
- Pharyngeal jaw — an extra set of teeth in the throat
Apart from these basic features, cichlids are as different as can be in terms of their sizes, colors, shapes, and behaviors.
Traditional convict cichlids have black and white stripes across their bodies. Yellow and black striped varieties also exist in the aquarium trade.
The typical convict cichlid size depends on the sex. Males are usually larger than females. Males can grow to be over 4 inches, but a more reasonable average for both sexes is about 3.5 inches long.
We don’t have good data on the average convict cichlid lifespan out in nature. In captivity, many cichlids live for at least 10 years. Be prepared for a long-term commitment before deciding to keep convict cichlids in your home aquarium.
The Best Convict Cichlid Diet
Convict cichlids are omnivores. This means that they eat both plants and animals in their natural environments. This includes:
- Small fish
- Aquatic plants
These fish aren't picky. They quickly adapt to local food supplies when they enter new environments.
In an aquarium setting, you can buy a wide variety of commercial flakes and pellets that are formulated for cichlids. Expect to feed your tank once or twice a day.
One fun fact about the convict cichlid diet is that researchers have used it to demonstrate early altruistic behavior in the species. Altruistic behavior is the kind that benefits the community as a whole instead of just the individual that’s involved in the decision. For example, male convict cichlids were far more likely to request food for unknown females as well as themselves — instead of just for themselves — when given the choice between the two options in a controlled experiment.
Basics of Convict Cichlid Care
Convict cichlids do best when kept in pairs. Your fish will be much happier and healthier with another convict cichlid around. But before you bring your new pets home, get your aquarium set up and ready to go.
Your basic convict cichlid aquarium should involve:
- At least a 70-gallon tank for two convict cichlids — some experimental setups keep mated pairs in 75-gallon tanks
- A water pH between 7 and 8
- A temperature that’s maintained somewhere between their native range of 68 degrees Fahrenheit to about 97 degrees Fahrenheit — one experiment found that convict cichlids grew the best when they were kept at 79 degrees Fahrenheit, and another had no trouble keeping them alive at 68 degrees Fahrenheit
- Clay pots and rocks provide places to hide and lay eggs
- A light source — scientific setups maintain the fish with 12 hours of light and 12 hours of darkness each day
- A good filtration system
Change your water regularly to help maintain these conditions. You can monitor your tank's environment with equipment like thermometers and chemical test strips. Even slight changes in pH and temperature can affect these tropical fish. For example, varying the temperature can influence the sex ratio of young convict cichlids.
Once you’ve decided that you want to raise convict cichlids, you’ll need to find a good source. You can always try local pet stores or contact an ornamental fish hatchery if you’re looking for a lot of these fish.
In general, convict cichlids are one of the easiest cichlid species to care for. But they still require plenty of time and attention — just like any pet. Take the time to research all of the aquarium-ready members of the cichlid family before deciding that the convict cichlid is right for you.