An exotic beauty, the mature Green Terror will display a rainbow of exquisite colors!
The Green Terror Aequidens rivulatus is a most beautiful fish with an overall green and blue metallic sheen. In addition, they have a magnificent array colors that can be purple, pink, red and/or electric blue. The males are the most colorful of this species and develop a brilliant red edging on their tail fin, but the the females are also quite striking.
This species tends to be confused with its very similar looking relative, the Blue Acara Aequidens pulcher. For a time it was actually known as the A. pulcher, but is now recognized as an independent species. Though they look very similar in many aspects, there are some key differences between these two fish.
In color the Blue Acara is mostly a steel blue-gray, with less of the green sheen seen on the Green Terror. The Green Terror is larger, reaching up to about 10 - 12" (25 - 31 cm) in length in the wild, while the slightly smaller Blue Acara only gets to be about 8 inches (20 cm). A mature Green Terror develops a more pronounced hump on its head while the Blue Acara retains a more sloped forehead. In addition, the Green Terrors are also significantly aggressive than the Blue Acara (one of the reasons for the name "Terror").
This colorful cichlid is a hardy fish that is moderately easy to care for. It's a rewarding specimen for the more experienced aquarist to keep as long as the water quality is maintained and they are provided a high quality diet. They are a ready feeder and if bred they become excellent parents, though they are known to sometimes be a bit lax with their first clutch of eggs.
As is typical with most large cichlids, the Green Terror is aggressive and requires a large aquarium. When young they can readily be kept in a community tank with other South American cichlids, but as they mature the become very belligerent and should be seperated into their own tank or into a tank with similarly sized and aggressive tank mates. They need at least 30 to 40 gallons of space just for themselves when kept as a single fish. As a pair they will need at least 75 gallons or more so as not be so aggressive, and even larger if kept with other large similarly aggressive tankmates.
The aquarium water should be neutral to slightly acidic, a little on the softer side, and have a moderate amount of current. They are fine with normal lighting and a gravel substrate. Provide lots of rockwork with caves and hiding places but be sure to leave an open area for swimming. Sunken driftwood can be used not only as a decoration but also as a water conditionting agent to help keep pH down in a too neutral aquarium.
For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care
Green Terror Again
Report Broken Video
Short video of a fairly large and colorful Green Terror
The video showcases both sides of this large and vibrantly colored Green Terror. With the lack of a bump on the head, it seems we are looking a female Green Terror. Quite a few nice shots and closeups!
- Size of fish - inches: 12.2 inches (30.99 cm)
- Minimum Tank Size: 40 gal (151 L)
- Temperament: Aggressive
- Aquarium Hardiness: Moderately hardy
- Temperature: 70.0 to 80.0° F (21.1 to 26.7° C)
- Aquarist Experience Level: Intermediate
- My Aquarium - Enter your aquarium to see if this fish is compatible!
The Green Terror Aequidens rivulatus was described by Gunther in 1860. They are found in South America; western Ecuador and central Peru. This species is not listed on the IUCN Red List.
They inhabit rivers, starting at the Pacific slope from the Esmeraldas River in Ecuador to the Tumbes River in Peru. Though, there is some speculation that the species in the Esmeraldas may not actually be a Green Terror but instead is its own distinct species, but this has not yet been fully substantiated. They are absent from many coastal streams that contribute a higher pH, as this is something Amazonian cichlids cannot handle. These fish inhabit the mostly still waters of both turbid and clear flowing stream basins where they feed on worms, crustaceans, and insects.
- Scientific Name: Aequidens rivulatus
- Social Grouping: Pairs - The females will sometimes become extremely aggressive towards their mate, particularly during spawning, so keep a constant eye on their behaviors.
- IUCN Red List: NE - Not Evaluated or not listed
The Green Terror is a deep bodied fish with pointed anal and dorsal fins. They are a good sized cichlid and tend to reach just over 12 inches (31 cm) in the wild, though in the aquarium they are typically about 6–8 inches (15 - 20 cm) and have a life span of about 7 - 10 years, though there are reports of them living more than 10 years if well cared for.
This is a very colorful deep bodied fish marked with various striping on its body and face. The male has a green and blue metallic sheen, a blue anal fin, and a red band at the edge of its tail fin. In addition, mature males will develop a rounded hump on their heads. The female has a darker tone with a green anal fin, no red band along the edge of its tail fin, and are generally a little smaller than the male.
All cichlids. along with some saltwater fish such as wrasses and parrotfish, share a common feature of a well-developed pharyngeal set of teeth located in the throat, along with their regular teeth. Cichlids have spiny rays in the back parts of the anal, dorsal, pectoral, and pelvic fins to help discourage predators. The front part of these fins are soft and perfect for precise positions and effortless movements in the water as opposed to fast swimming.
Cichlids have one nostril on each side while other fish have 2 sets. To sense "smells" in the water, they suck water in and expel the water right back out after being "sampled" for a short or longer time, depending on how much the cichlid needs to "smell" the water. This feature is shared by saltwater damselfish and cichlids are thought to be closely related.
- Size of fish - inches: 12.2 inches (30.99 cm) - In the wild the maximum size for these fish is about 12.2 inches (31 cm). Males will reach up to about 10 - 12" (25 - 31 cm) and females will reach 7 - 9" (18 - 23 cm). In the aquarium the typical size is smaller at about 6–8 inches (15 - 20 cm).
- Lifespan: 10 years
Although the Green Terror is a stunning fish and draws the attention of all levels of fishkeepers, it may not be for everyone. They are large and extremely aggressive fish, requiring a large amount of space to themselves and are only suitable for similarly large and aggressive tank mates. In pairs, particularily, they are known to "terrorize" (hence their name) the other fish in their aquarium. In addition, the Green Terror is extremely sensitive to water condition changes and needs a very stringent maintenance schedule. Due to these restrictions and obstacles, it is recommended that Green Terrors be housed by fish keepers with a significant amount of experience in keeping large and aggressive cichlids. That being said, this fish is still able to thrive and do well in an aquarium maintained by a begginner as long as that beginner is diligent in maintenance and knowledgeable concerning size and tank mate restrictions.
- Aquarium Hardiness: Moderately hardy
- Aquarist Experience Level: Intermediate
The Green Terror is primarily a carnivore that can be fed a variety of foods, but they do tend to be picky. They will eat frozen foods like krill, bloodworms, and brine shrimp as well as flakes, plankton and green vegetables. They can also be fed cichlid pellets. For the best color offer live red earthworms.
Do not feed beef hearts or other red meats to this fish, foods high in protein can cause issues in the digestive system.
Feed young fish 2 to 3 times a day and adults 1 to 2 times a day. Feeding in smaller amounts several times a day instead of a large quantity once a day will keep the water quality higher over a longer time. All fish benefit from vitamins and supplements added to their foods.
- Diet Type: Carnivore
- Flake Food: Yes
- Tablet Pellet: Yes
- Live foods (fishes, shrimps, worms): Most of Diet
- Vegetable Food: Some of Diet
- Meaty Food: Most of Diet
- Feeding Frequency: Several feedings per day
The Green Terror are fairly easy to care for provided their water is kept clean, though they are very sensitive to deterioating tank conditions. To help combat this sensitivity, make sure to use an efficient biological filter coupled with a stringent maintenance schedule. Aquariums are closed systems and regardless of size all need some maintenance. With home aquariums the nitrate and phosphates build up over time and the water hardness increases due to evaporation. Because these fish are very sensitive to pollutants and pH instabilty, it is important that at least 15 - 20% of the tank water should be replaced bi-weekly, and weekly if the tank is densely stocked. When doing the weekly water changes always use a gravel cleaner to make sure all of the decomposing organic matter that has built up is removed. Condition replacement water properly and try to match the temperature of the tank water as close as possible. The majority of of problems that occur with tropical fish tanks usually come down to one cause, decomposing organic matter!
Use an algae magnet or scraper to keep viewing panes clear.
- Water Changes: Bi-weekly - 15 - 20%, weekly if tank is well stocked.
As with all large South American cichlids, Green Terrors need a lot of room, 30 or 40 gallons for an individual fish. A minimum of 75 gallons is suggested for a pair. An even larger aquarium will be needed if keeping them together with other large fish. They do best in water that is soft and slightly acidic to neutral. Provide low to moderate water movement and efficient biological filtration. They are fine with normal aquarium lighting and enjoy lots of rockwork with caves and hiding places. Use driftwood to help pull the pH down if you have very hard water. Be sure to leave an open area in the center for swimming. If setting up a large tank with other species, make sure to arrange the tank to block lines of sight as this will help divide the tank into "territories" and help quell aggressive tendencies.
- Minimum Tank Size: 40 gal (151 L) - 40 for a single fish and 70 for a pair.
- Substrate Type: Large Gravel
- Lighting Needs: Moderate - normal lighting
- Temperature: 70.0 to 80.0° F (21.1 to 26.7° C)
- Breeding Temperature: - 77 - 79° F (25 - 26° C)
- Range ph: 6.5-8.0
- Hardness Range: 5 - 13 dGH
- Water Movement: Moderate
- Water Region: All
As with all larger South American cichlids, adequate tank space is the most important element in lowering aggression. The Green Terror is a highly to moderately aggressive cichlid that can be kept with other large South American cichlids. Depending on their personality and the circumstances in which they grow up, they can actually end up relatively peaceful. They use their lateral line to determine how much space they have available to them, if they have "too little" they often become rather aggressive as adults; contrarily, if they have "enough" they tend to not be as aggressive once matured. With a bigger tank they have less of a need to "take someone out" so that they will have room to grow.
The Green Terror is generally aggressive toward those of the same species. It is possible that the female Green Terror is more aggressive than the males and should be kept singly unless breeding. If breeding, they will become very aggressive and need a very large tank or a tank of their own. Do not house with Green Terrors with African Cichlids as the Africans are too small and will be harassed or eaten. Green Terrors can be kept with Pacus, Plecostomus, Oscars, Silver Dollars, Gars, and other similarly sized fish and of a like temperment.
- Venomous: No
- Temperament: Aggressive
- Compatible with:
- Same species - conspecifics: Yes - Good if kept in pairs.
- Peaceful fish (): Threat
- Semi-Aggressive (): Threat
- Aggressive (): Threat
- Large Semi-Aggressive (): Threat
- Large Aggressive, Predatory (): Monitor
- Slow Swimmers & Eaters (): Threat
- Shrimps, Crabs, Snails: Threat - is aggressive
- Plants: Monitor - Will uproot plants that are not secure.
There are a few differences between male and female Green Terrors, including the red band around the male's tail fin. In addition, males will have blue anal fins while females have green anal fins, males tend to be a bit larger than females, and males will develop large, rounded humps on their heads while the females will not. One unique aspect of the Green Terror females is that they are actually more aggressive than the males, particularily when spawning. Normally this tendency is switched.
The Green Terror has been successfuly bred in captivity for many years. They are egg layers and open breeders, meaning the female deposits the eggs and the male fertilizes them in the open water. To ensure you have at least one viable male/female pair, it is recommended to obtain several juveniles and allow them to pair up at their own pace. The breeding water should be slightly acidic with a pH of 6.5, soft to medium- hard at between 4 - 12° dGH, and have temperatures between 77 - 79° F (25 - 26° C). The parents will clean off a flat rock to spawn on and will lay up to 400 eggs. The fry hatch in 3 - 4 days and are free swimming by 11 days. during which time the parents will both be attentive and protective of their young. Perform frequent water changes. Feed fry newly hatched brine shrimp, crushed flake, and fry food. The fry grow slow initially until about 1/2 to 3/4 inches (2 cm) but then will grow at an accelerated pace. See a general description of how cichlids breed in: Breeding Freshwater Fish: Cichlids.
- Ease of Breeding: Moderate
Green Terrors are subject to infections as well as other diseases that affect ail freshwater fish, especially if the water is of poor quality and low oxygenation. One common problem is Ich. It can be treated with the elevation of the tank temperature to 86° F (30° C) for 3 days. If that does not cure the Ich, then the fish needs to be treated with copper (remove any water conditioners). Several copper based fish medications are available for Ich. Copper use must be kept within the proper levels, so be sure to follow the manufacturers suggestions. A copper test also can be used to keep the proper levels. You can also combine increasing the temperature with an Ich medication treatment.
Hard water will contribute to the notorious Head and Lateral Line Erosion (HLLE) or 'Hole-in-the-Head' disease, an ailment that large cichlids are prone to. Intestinal disease can be treated with metronidazol.
As with most fish the Green Terror Cichlids are prone to skin flukes and other parasitic infestations (protozoa, worms, etc.), fungal infections, and bacterial infections. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria or harmful chemicals. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.
The Green Terror is readily available both online and in fish stores. They are moderately priced as juveniles and become slightly more expensive at they mature.
- Animal-World References: Freshwater Fish and Plants
- Dr. Rüdiger Riehl and Hans A. Baensch, Aquarium Atlas Vol. 1, Publisher Hans A. Baensch, 1991
- George Zurlo, David Schleser, Cichlids (Complete Pet Owner's Manual), Barron's Edu Series, 2005
- Richard F. Stratton, The Guide to Owning Cichlids, T.F.H. Publications, Inc., 2002
- Glen S. Axelrod, Brian M. Scott, Neal Pronek, Encyclopedia Of Exotic Tropical Fishes For Freshwater Aquariums, TFH Publications, 2005
- Aequidens rivulatus (Günther, 1860) Green terror, Fishbase.org
- "Aequidens rivulatus", Malawi Cichlid Homepage, The Art and Science of Fishkeeping, Referenced online, 2007
- "Green Terror", Central Pets Educational Foundation and its licensors Referenced online, 2007, http://www.centralpets.com/animals/fish/freshwater_fish/fwf4618.html