How Many Green Terrors Can Be Kept in A Tank

Green terror fish, also known as Andinoacara rivulatus, are strikingly beautiful cichlids native to the warm waters of South America. Their vibrant green and blue hues make them popular among aquarists, but their aggressive nature requires careful consideration when choosing tank mates.

These green terror cichlids are known for their territorial behavior, especially during breeding, and can be quite aggressive towards other fish. However, green terrors can thrive in a home aquarium with the right tank setup and companions.

In this blog, we’ll try to figure out how many green terror fish are in a given tank and provide you with some useful information to nurture them effectively.
green terror

Is Green Terror Fish Aggressive?

Yes, green terror fish are said to be aggressive.

They are territorial fish and chase other fish even if they are not a threat. The fins can nip smaller fish and the bigger ones can even chase them. These fish are also considered predatory fish and eat smaller fish that are caught in the same place.

Green Terror fish defend their territory and can act very aggressively when they are breeding. The male will mostly be being aggressive towards the female.

1. Habitat

Green terrors (Andinoacara rivulatus) are garden fish that originated from the Amazon and Orinoco basins in South America. They live in places where the water is slow and acidic and when there is plenty of cover like reefs or driftwood.

2. Temperament

They are often extremely aggressive towards their tankmates or even their reflections, once they consider them a threat. This may result in trailing and splashing the water as a result. Being a predatory species, they will eat pretty much anything smaller they can catch. Males will continue to pursue females, and both will become protective of their membranes and fry.

3. Tank Size

On account of their large size and predatory nature, these fish need a large aquarium. A 75-gallon tank is the minimum size recommended, and it can house just a single fish. If you have additional tankmates, it suggests an even bigger tank.

4. Dietary Needs

Green terrors are omnivores and require a varied diet that includes both meaty and plant-based foods. Here are some options to consider:

Brine shrimp (live or frozen) Bloodworms (live or frozen) Pellets Chopped veggies like zucchini and spinach
Blackworms (live or frozen) Spirulina flakes Flakes

Green Terror Size

Green terror cichlids are relatively large fish, with males reaching a bigger size than females.

Males can grow up to 12 inches (30 cm) in length. They will also develop a nuchal hump on their head and very pointed dorsal and anal fins. While Females are smaller, reaching around 4.7 inches (12 cm) at sexual maturity.
green terror cichlid

How Many Green Terror Fish Are in A Tank?

The bare minimum required size of a tank for a single Green Terror fish is 75 gallons. They can be even longer, up to 12 inches, and are moderately quick swimmers.

Green Terrors tend to be very aggressive, particularly in the event of fish of similar size. If you want to keep it with the tankmates, then you certainly need a much bigger tank just to make the territory where all the fish can play equally. In general, it is recommended to count an extra 100 gallons for each tank mate.

Here are some additional factors to consider:

  • Filtration: Green Terror Cichlids are fish that eat too much and give off a lot of waste. To have clean and healthy water, you will need an aquarium filter system that can deal with the fish waste.
  • Water quality: It is worth mentioning that the Green Terrors are spoiled by low-quality water. This entails doing regular water changes to ensure the water parameters have the optimal levels.
  • Temperament: Green Terrors are territorial and aggressive during breeding. Usually, they are vicious. If the fin-nipping or chasing behavior is observed, you should take some fish out of the tank.

Green Terror Tank Mates

Some good options include larger, more robust fish such as other cichlids like Severums, Jack Dempsey, or Firemouth cichlids. These fish can hold their own against the Green Terror and are less likely to be bullied.

Additionally, catfish like Plecos or Bristlenose catfish can also make good tank mates, as they tend to stay towards the bottom of the tank and out of the Green Terror’s way.
Green Terror and Oscar

Green Terror and Oscar


  • Temperament: Both of them are characterized by their audacity and territoriality. They tend to be quite aggressive, in particular towards their kin as well as smaller fish.
  • Size: They get to a similar length, with green terrors able to grow up to 12 inches and Oscars reaching up to 14 inches.
  • Diet: Both are omnivores and feed on a wide range of meat as well as a blend of pellets and flakes.
  • Care requirements: They are both common to the same water parameters requirements, which is why they prefer the water to be hard and slightly alkaline.


1. Aggression

Green terrors and Oscar are categorized among the more aggressive cichlids. The Oscars are a peaceful variety of fish and don’t have the potential to jeopardize the other fish in the aquarium unless it depends on the particular fish.

2. Appearance

The elegance of the green terror will perhaps be the most discernible characteristic of this fish species. This is because they are more streamlined and have a body color that ranges from blue, to green, and brown. The Oscar represents a proportional body with a wider range of colors that includes crimson, orange, and albino.

3. Compatibility

In a very large tank (over 150 gallons), the two can be kept together, but it’s not advisable for beginners due to the chance of aggression.

Here’s a quick summary table of Green Terror and Oscar fish:

Feature Green Terror Oscar
Temperament More Aggressive Moderately Aggressive
Size Up to 12 inches Up to 14 inches
Diet Omnivore Omnivore
Water Parameters Hard, Alkaline Hard, Alkaline
Appearance Streamlined, Blue/Green/Brown Stocky, Varied Colors
Compatibility Not ideal for tank mates Not ideal for tank mates

In summary

In this article, we have discussed Green Terror fish in detail and provided you with information about the number of Green Terror fish you can keep in a tank. Green Terror fish are renowned for their beauty, and they are the top choice to make any aquarium an aesthetic place. Since these fish are aggressive, they need more attention and care than normal. Additionally, you need to research and find their tank mate to avoid any unwanted situation in the tank.

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