Green terror

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: sand.

Behavior

Plant interaction: destroys most plants.

Feeding

Carnivore-leaning omnivore. Cichlid pellets (large, high-protein) form the staple diet. Supplement with frozen prawns, frozen mysis, frozen bloodworm (for juveniles), live earthworms, and live feeder shrimp. Larger adults take whole market shrimp, mussel, and fish fillet. Blanched peas and spinach provide fiber. Feed once or twice daily for adults. Juveniles benefit from 2-3 smaller feedings. The green and blue body coloration intensifies on a varied diet with carotenoid-rich foods (shrimp, krill, astaxanthin-enhanced pellets). Avoid feeder fish as a routine food source; they carry disease and parasites and provide poor nutrition compared to prepared foods.

Compatibility

• Seriously aggressive. The common name is not marketing hyperbole. Males become increasingly territorial as they mature and will dominate a tank of 300 L if not matched with equally assertive tankmates.
• Not a community fish in any conventional sense. Tankmates need to be large, robust, and able to hold their own: other large South American cichlids (oscars, severums, geophagus), large catfish (pleco species, synodontis), and large loaches. Anything small enough to fit in the mouth is food.
• Breeding pairs are significantly more aggressive than single specimens. A male-female pair defending eggs or fry will attack everything in the tank, including fish twice their size. Dedicated species tanks are the safest option for a breeding pair.
• Males reach 25–30 cm and develop a pronounced nuchal hump (forehead bump) with age. Females stay smaller at 15–20 cm. The size difference and the hump make sexing adults relatively easy.

Origin and habitat

Andinoacara rivulatus is a large, aggressive cichlid from the Pacific slope of South America, ranging from the Esmeraldas drainage in Ecuador south to the Tumbes River in northern Peru, with records across the Guayas, Santa Rosa, and Zarumilla basins. Gunther described it in 1860 as Chromis rivulata. The green terror name is muddled by a close relative: Andinoacara stalsbergi, split off as its own species in 2009, lives further south in Peru and is often regarded as the true green terror in the hobby. The two are told apart by their scale and fin patterns, A. stalsbergi having pale-centred scales with dark edges and a narrow, sharp white fin margin, while A. rivulatus shows the reversed scale pattern and a gold-orange or white fin edge, the basis for the gold-saum and white-saum trade forms. Males are considerably larger than females and grow a tall nuchal hump as they mature; in the wild that hump comes up mainly in the breeding season, but tank-kept males often carry huge permanent ones. Records list a maximum around 20 cm, though aquarium males are frequently reported larger, to roughly 25 to 30 cm, with females staying smaller.

Breeding

A substrate spawner with strong biparental care. The pair cleans a flat rock or digs a pit and the female lays a large clutch, up to several hundred eggs, which she tends while the male holds the territory. The eggs hatch in three to four days, the fry are moved to a pit until they are free-swimming a few days later, and both parents herd them around for weeks afterward. Breeding itself is not hard in a dedicated pair tank, but the aggression is extreme, and a spawning pair will batter anything else in the tank. The real difficulty is pairing the adults safely, since a male will often kill a female that is simply dropped in with him; the usual approach is to raise a group of six or more juveniles and let pairs form on their own. Broods are large, so finding homes for the young becomes a quick necessity.

Common problems

Managing aggression is the central challenge. A single green terror among other large, robust cichlids in a big tank is workable; a breeding pair turns the whole tank subordinate and needs its own space. Tank size is the other common mistake, since a single adult wants a large tank and a pair more still. Like other big cichlids kept in poor water, they can develop hole-in-the-head erosion along the lateral line and head, which is linked to water quality, diet, and chronic stress, so clean water and a varied diet are the best prevention. New fish may carry ich, which the species handles well under standard treatment.

Bioload

Further reading

• Stocking ideas by tank size