Comprehensive Guide to Keeping Green Terror Cichlids

Origin, Size, and Classification

The Green Terror Cichlid naturally comes from South America, specifically from regions spanning Peru to Ecuador. Their body shape is typical of cichlids from this area. As juveniles, they closely resemble the Blue Acara, and are sometimes mistakenly identified as such. However, as they grow, it becomes clear they are different species.

An adult Green Terror can reach a size of 30 cm (12 inches), which is larger than the adult Blue Acara. They also display a greener hue compared to the Acara. Their scientific name is Aequidens rivulatus. Like many cichlids, male Green Terrors develop pronounced foreheads, forming noticeable nuchal humps as they mature and display to females. Young fish may show a bluer coloration that changes over time.

The scales of the Green Terror have a sparkling quality, reflecting light and shifting from plain green to bluish-green depending on the angle. Their underbelly can exhibit pink or brown tones, with distinctive patterns on their cheeks and lateral lines running along their bodies.

Given their potential large size, it's important to house Green Terrors in adequately sized aquariums. We will discuss appropriate tank setups in later sections of this article. Choose tank mates carefully; avoid pairing them with peaceful or easily stressed species, as Green Terrors can cause stress leading to disease in other fish.

Setting up an Aquarium for the Green Terror Cichlid

When buying Green Terror Cichlids, most aquatic stores offer them as juveniles. At just a couple of inches long, they might seem small, but they grow significantly. Adult males can reach 8-10 inches (20-25cm), with females slightly smaller. Keep this in mind when choosing an aquarium. While juveniles can thrive in a 50-gallon (about 230-liter) tank, adults need at least a 100-gallon (around 455-liter) tank. Ensure the tank is at least 48 inches (122 cm) long, though 60 inches (152 cm) is better, to give them enough swimming space. The tank should also be deep enough for the fish to turn around easily. The substrate choice isn’t critical, but make sure any gravel is smooth and rounded to prevent injury, as these fish are constant diggers. Sharp edges can cause harm. Although they tend to uproot plants, having vegetation in the tank provides excellent cover. You might want to consider synthetic plants unless you can secure live plants with weights. Adding rocks or wood is also good, but place them before adding the substrate to prevent them from toppling if the fish dig underneath.

As with other large cichlids, the Green Terror is considered a high waste producer, so the filtration system must handle the increased bio-load. An external or canister filter is recommended, and make sure the tank is fully cycled before introducing the fish. Regular water changes are essential - at least 10% weekly. If nitrate levels rise, increase the water change until they stabilize at an acceptable level.

Green Terrors do not need high water temperatures. They thrive in a range of 20-24 °C (69-75 °F), but keeping the temperature on the higher end is advisable. They can tolerate a fairly broad pH range compared to some fish, but avoid extreme levels to maintain their health. A pH range of 6.5-7.5 is ideal.

Green Terrors can be kept alone without issue. However, if you want to add tank mates, choose carefully. Only add fish that can stand their ground and are similar in size to the Green Terror. Other cichlids of similar size make good tank mates, but avoid overcrowding the tank. Each fish will need its own territory, so place décor strategically to help with this. Introducing the Green Terror after other fish are already established can also help reduce aggression since it won’t have a chance to claim territory first. It’s also advisable to keep a single Green Terror if other fish are in the tank. If a male and female pair up, their breeding can cause significant aggression issues.

Sexing and Breeding the Green Terror Cichlid

Determining the sex of Green Terror Cichlids is relatively straightforward if you have some experience with them, though even seasoned keepers can sometimes make mistakes. Here are a few tips to help identify the sex of your fish. As mentioned earlier, males typically grow larger than females when fully mature. However, this characteristic isn’t useful when the fish are juveniles, which is when most people purchase them.

More reliable signs appear as the males mature. Their fins, especially the dorsal fin, become more elongated, and they usually exhibit brighter colors than females. Some mature males also develop a small nuchal hump on their foreheads. While females tend to look duller, the best way to obtain a breeding pair is to purchase a small group of juveniles, allow them to grow, and let them pair off naturally.

Green Terror Cichlids are egg layers, and once they get the hang of parenting, they will diligently care for their eggs and young. Flat rocks in the tank make ideal spawning sites, and the parent fish will clean these surfaces before the female lays her eggs. Raising the water temperature by a few degrees can encourage spawning, but don’t expect perfect results with the first few batches. They’ll become good parents over time, so patience is key.

After the eggs are laid, the female usually guards them while the male patrols the area, keeping potential threats at bay. The eggs should hatch within 3-4 days. Any that remain white are either unfertilized or have developed fungus and should be removed from the tank.

When the fry hatch, they’ll initially feed on their yolk sacs, so you don’t need to provide food until they begin swimming freely. At this stage, it might be wise to remove the parent fish and raise the fry on your own. Maintain excellent water quality, as the fry are very sensitive. Perform regular water changes and remove any uneaten food promptly to prevent it from spoiling the water. You can feed the fry newly hatched brine shrimp or finely crushed flakes. Remember, they have small stomachs, so offer small portions several times a day, about 3-4 times daily.

The fry may grow slowly at first, but once they reach just under an inch in size, their appetite will increase, and their growth will accelerate. When the juveniles reach 1.5-2 inches (~4-5cm) in size, they can be moved to other tanks or passed on to other fish keepers.

General Notes

While Green Terror Cichlids can adapt to a variety of water conditions, this doesn’t mean they can tolerate poor water quality. Always test the water regularly and ensure that it remains high in quality.

If you don’t have a plan for rehoming the young Green Terrors, it’s best to reconsider breeding them. Overcrowding in the tank can lead to increased aggression, so it’s much better to keep these fish in an environment where they have ample space to establish their own territories.