Among the most famous freshwater fish, cichlids are known for their diversity of colors and body shapes. Since they tend to be aggressive and some can grow quite large, choosing the correct tank size is crucial to keep them healthy. The best cichlids for a 20 gallon tank are small ones, mostly dwarf varieties. Small cichlids like rams and kribs can work well (more on that in a moment!) but larger ones like Oscars are way too big for a tank of this size.
Most of the cichlids I’m recommending for a 20 gallon tank are best suited to live in the tank as a pair, perhaps with a few other carefully selected community fish. It’s common to use a tank of this size for juveniles while they grow, moving them into a larger tank as they get bigger – But the fish on this list are all cichlids that can live in a 20 gallon tank as adults.
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2. What Are the Best Cichlids for a 20 Gallon Tank?
2.1 Ram Cichlids
Ram cichlids are known for their peaceful nature and gorgeous coloration. They’re easy to keep and care for – especially in comparison to other cichlids – because they’re less aggressive, undemanding and amiable. Like most cichlids, they need warm water in the aquarium with a temperature between 71°F- 82°F and as such, require a heater.
German blue rams are one of my personal favorite fish. Their color combination is stunning, and this, combined with their easy compatibility with other peaceful community fish with similar parameters (corys, plecos, tetras, etc) put them at the top of this list.
The only downside is that due to inbreeding in the trade, they’re not as hardy as other fish and will live a maximum of 4 years (probably closer to 2-3). You can keep a pair in a 20 gallon community tank; Remember to give them lots of hiding places and plants to avoid any territory issues with other tankmates. Rams aren’t aggressive by nature, but they may develop it if a tank is overcrowded or they don’t have suitable conditions (like plants to break up the line of sight in the tank).
2.2 Convict Cichlids
These popular cichlids get their name from the distinct, dark vertical bands that stripe their bodies, making them look like “convicts” wearing an old-school blank and white striped prisoner’s uniform. Convict cichlids are also intensely aggressive – So much so that scientists often go to them when studying aggression in fish.
Convict cichlids are a great option for a 20 gallon tank because of their small size: They reach around 4 inches when fully grown. You can keep a single convict cichlid in a 20 gallon tank, or a breeding pair, but not more than that. These are NOT community fish. They can be straight up violent, attacking, injuring, and even killing other fish.
Despite this, they’re a good beginner fish because they’re very hardy and easy to breed; They’re also very active in the tank, which makes them fun to watch. Keep lots of driftwood, plants, caves, and other hiding spots available to the convicts to keep any aggression at bay. Give them the right environment, and they’re an excellent choice for a 20 gallon tank.
You can see a slight size difference between males and females, and these fish can have a long lifespan: Anywhere from 8 to 12 years, depending on the quality of care you provide and how well they were bred.
Convicts need water temperature between 79°F-84°F with pH levels between 6.5-8.
2.3 Cockatoo Cichlids
Like their namesake, cockatoo cichlids have an upright, slightly spiked dorsal fin that resembles the feathers on a cockatoo bird. This, with their bright color combinations, give them an exotic look – And because of their small size, I’d definitely recommend them for a 20 gallon tank. Males reach 3.5 to 4 inches when fully grown, and females are a little smaller.
Cockatoo cichlids look very similar to other dwarf cichlids, and you can keep a pair in a 20 gallon tank with ease. They can sometimes have a reputation for aggression, but this comes out mostly during breeding or when kept in stressful situations. They should be kept with peaceful species to minimize stress and aggression.
Selecting breeding has created a variety of colors ranging from red and orange to blue. In a 20 gallon tank, I’d probably only keep a pair. Bear in mind they should have a sand substrate; Since they like to scavenge the bottom, they can injur themselves on gravel.
Cockatoo cichlids like warm water and are sensitive to fluctuations in water temperatures and pH; They require between 79°F to 84°F and a pH between 6 to 7.
2.4 Umbrella Cichlids
Another beautiful dwarf cichlid apistogramma borellii are an unfussy South American cichlid that loves sandy bottoms and can work well in a planted tank. In a 20 gallon tank, you can keep a pair of umbrella cichlids. If you want to create a community tank around them, you’ll need a larger tank size; They can get along well with other peaceful species, but they need lots of space in order to do so.
You might also hear them referred to as “yellow dwarf cichlids” – Not to be confused with yellow lab cichlids:) Readily available in the aquarium trade, they’re popular for their bright coloration and undemanding care. Soft pebbles, sandy substrate, driftwood, and plants will help create a suitable habitat for umbrella cichlids. They need a temperature between 68°F to 82°F and a pH of 6-8.
Sometimes even pairs will nip at each other’s fins. Like most cichlids, they should be kept from other fish during breeding as they can become quite aggressive during this time.
2.5 Dwarf Cichlids
There are lots of other varieties of dwarf cichlids in addition to the ones I’ve mentioned so far, and many are great candidates for a 20 gallon tank because of their small size. Most male dwarf cichlids grow to be around 2 inches long; Females are smaller than the males. “Dwarf cichlid” refers to cichlids that don’t grow larger than 10cm; They’re usually called apistogramma, and you’ll see this name in front of many dwarf cichlid varieties: apistogramma cacatuoides, apistogramma agassizii, apistogramma bitaeniata, and so on – Though there are even more dwarf cichlids beyond this, such as nannacara and dicrossus.
In a 20 gallon tank, you can keep a single pair of most kinds of dwarf cichlids. Depending on the variety, you may also be able to keep the pair with some additional peaceful tank mates in a tank of this size, such as shrimp or cory catfish. Because cichlids tend to be aggressive, they require more space and will quickly become stressed in an overstocked environment.
Most dwarf cichlids tend to hang out near the bottom, and will do well with sandy substrate, hiding spots, driftwood, and plants that help replicate their warm, freshwater native habitats.
They require aquarium water with a temperature between 72°F-77°F and a pH of 6.0 to 7.2.
2.6 Kribensis Cichlids
Kribensis cichlids are not to be missed, and they’re my runner up choice for cichlids for a 20 gallon tank, after rams. Their colors and patterning are just incredible. A picture says a thousand words: They have a bright pink spot on their bellies, with neon yellow-green running from its edge up to the face, and purple, orange, and yellow coloration on the fins, with black spots on the dorsal and caudal fins.
Also known as “rainbow cichlids,” kribs are very peaceful but tend to be active, so they can be stressful for slow-moving tank mates. In a 20 gallon tank, you can keep a pair of kribs along with a few other small, peaceful tank mates that won’t be bothered by the kribs’ active swimming (cory catfish, plecos, Siamese algae eaters, some rasbora).
Kribs can be fin nippers, so avoid keeping them with any long-finned fish. Other than that, they’re an excellent member of a community tank. Their water temperature should be between 72 °F to 79 °F, and pH should be 5.0-8.0.
This curious bottom dweller is from rocky shorelines in Lake Tanganika in Africa. You’ll often hear julidochromis referred to as “Juli cichlids,” or just “Juli’s.” They reach a maximum size of 2.5 to 3 inches, and are best kept as bonded pairs placed together as juveniles. In other words: Buy a juvenile male and female for the 20 gallon tank, and let them grow up together. It can take around a year for the pair to bond, but once they do, they mate for life.
Julis need a tank setup with lots of rocks and rocky caves to replicate their natural Africa habitat, and they’ll spend time hanging out in and around the rocks (they’re also a little shy!)
Like other cichlids, they can be territorial if they don’t have enough space. Julis can be good members of a community tank, but they’d need something larger than 20 gallons. For a 20 gallon tank, I’d stick with a bonded pair. These fish require water with a pH of 8.0-9.0 and a temperature of about 76 °F.
3. What will happen if a 20-gallon tank is overstocked with bigger cichlids?
Overstocking is a big no-no in the aquarium hobby, and a 20 gallon tank is no different. Unfortunately, many people still do it, mostly out of ignorance and a lack of understanding of what humane conditions are for fish. Putting too many fish in the tank can cause aggression, illness, and even death. Let’s take a look.
Overstocking cichlids in a 20 gallon fish tank can cause them to suffocate due to lack of oxygenation and poor water quality (creating nitrates, etc) that result from an overstocked tank. Fish breathe from the water in the same way we breathe from the air. If the water doesn’t have enough oxygen, the fish can’t breathe.
Cichlids are well known for their aggressive and territorial behavior, so they’re among the least tolerant to crowded conditions. In a tank as small as 20 gallons, adding too many fish is a recipe for disaster. They’ll chase each other for territory, fight and injure each other, and stress each other out until one of them finally gets sick. If there’s a significant difference in size, the bigger fish may be more likely to simply eat the smaller one.
Speaking of stress… If you don’t provide enough space for your cichlids to swim freely, have their own hiding spots, and to break up the line of sight, they can develop stress as a result of living in an environment that doesn’t make them feel comfortable and safe – Even if they’re not overtly fighting. This lowers their immune response and makes them more likely to become sick and die.
3.3 Poor Water Quality/Extra Waste Production
Cichlids for the most part are not a low bioload fish. In other words, they produce a lot of waste. When you put too many in a single tank, it’s harder to keep good water quality, and the extra waste creates toxic compounds that are dangerous for the health of the fish.
4. Best Cichlids for a 20 Gallon Tank: FAQs
4.1 What Cichlids Can Go In A 20 Gallon Tank?
Cichlids that can live in a 20-gallon tank include most dwarf cichlids, ram cichlids, convict cichlids, cockatoo cichlids, umbrella cichlids, kribensis cichlids, Julidochromis, and more. Look for dwarf cichlid varieties (this means they don’t grow to be over 10cm in size).
4.2 Why Can’t You Keep A Bigger Cichlid In A 20 Gallon Tank?
Just because a human could live in an elevator doesn’t mean they should have to. Fish are no different. Bigger cichlids need bigger tanks in order to live a humane, healthy life. Without enough space, they’ll get stressed, sick, and have a reduced lifespan and low quality of life.
Being a fishkeeper is a significant responsibility. It may be tempting to put more cichlids in your 20 gallon tank, but please remember that they’re dependent on us for care, and that overstocking hurts the fish.
4.3 How Many Cichlids Can I Put In a 20-Gallon Tank?
For the most part, a bonded pair is a good choice for a 20 gallon tank. Attempting to keep more than two in such a small tank is a bad idea because of their tendency for aggression. Some dwarf cichlid pairs may be able to live with other peaceful community fish in a 20 gallon tank.
It’s good to have a pair of cichlids in a 20-gallon tank. Keeping more than two cichlids in a 20-gallon tank can be dangerous because of their aggressive behavior.