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Triangle Cichlid

Uaru amphiacanthoides

Uaru,     Photo by Darrell Ullisch


The Triangle Cichlid, Uaru amphiacanthoides, is a very graceful, peaceful, and attractive fish from the Amazon region.  In shape and behavior, they remind me of discus, and are found in the same waters as Discus and Angelfish.  They are very rare in nature.  They have a flat, oval body with a blunt head and small mouth.  An elongate triangle extends from behind the pectoral fin to near the base of the tail with separate spots at the tail base and behind the eye.  The pattern and color can vary both with the mood of the fish and with different strains.  Above and below this triangle the body is colored greenish yellow to brown to golden-yellow in varying intensities.  The long dorsal and anal fins are often dark colored and contrast nicely with the body.  With proper lighting (and mood), iridescent blue can be seen streaked in the dorsal, anal, and caudal fins.  During spawning, the triangle decreases in size and the body turns a much lighter golden-yellow and is very striking.  This fish is one of the most chameleon-like fishes I have ever kept, as the colors change frequently.  At times they have a golden-yellow eye, but at other times the eyes can be orange or red.  With poor health, mood, or water conditions, these fish can turn completely black.  Fry less than 2 inches are often colored much differently, with white polka dots on a rust brown body.


The Uaru is closely related to the Discus, and both of these fish share many traits.  They can be quite shy and secretive, they prefer warmer temperatures, and they have a graceful, almost majestic presence as they glide slowly through the aquarium.  Although Uaru like warm temperatures, they can be kept and bred in the low 80s’ and they don’t seem to be as sensitive to water conditions or as finicky eaters as Discus are.  In fact, Uaru would be an ideal fish for one to obtain and keep if one were thinking of adding Discus later.  A large tank of 50 or more gallons would be recommended for them since Discus can reach 8 inches and Uaru 10 inches.  Adult Uaru are shy and can be easily spooked if not in the right surroundings.  A dark background such as black plastic on the sides and back of the tank is important.  A heavy growth of floating plants such as water sprite is helpful to give them security from above, and a couple of large clay pots, wood pieces, or slate help provide hiding places.  Give the fish adequate swimming room so they will not hide all the time.  Live decorative plants should not be used, as they will be torn up and eaten by the adults.   Even fry as small as one inch will nibble away at softer plants.  Poor water quality, illness, shallow tanks, or too bright of lighting will cause nervousness in Uaru.  Gouramis, tetras, and peaceful South American Cichlids make good companion fish for Uarus and can help draw them out.


The diet of Uaru can be varied, although they are strongly vegetarian in nature.  They seem to do best with live plants (e.g. floating water sprite), a higher vegetable content dry food, and some meat.  I use Pond Chow pellets and frozen beef liver for the staples with occasional beef heart, frozen brine shrimp, frozen vegetables, or lettuce for variety.  Uaru fry 1 to 3 inches are especially gluttonous and aggressive feeders.  They will eat just about anything until their stomachs are quite distended.  They are thorough eaters also.  Cory catfish will almost starve in a tank with a number of Uaru fry in it, since there is nothing left over.  The fry like to school, and 6 or more of them increase their confidence and feeding aggressiveness.  Adults like to school also---until breeding!  Heavy feeding means pollution buildup and water changes are important.  Uaru are actually quite tolerant of some pollution, but they lose appetite and grow more slowly as nitrates increase.  They are much more sensitive to water chemistry changes than many fish, and moving them from tank to tank can be hard on them.  Water changes should be kept to 25% or less.  Uaru can tolerate a fairly wide pH range (4.5 to 7.6+) but they seem to do best and breed for me between 5.5 and 6.5 pH.  There are many ways to get water in the acid range such as RO units, rainwater, and peat moss filters.  The method that seems to work best for me is power undergravel filters with a mature biological base.  Over time, even regular city tap water can become acidic.  The 2 seventy gallon tanks that I keep my Uarus in each contain 2 powerheads for the undergravel plates with at least 3 inches of pea-sized gravel over the top.  Because Uaru are heavy feeders, debris and bacteria build up quickly in the gravel.  I partially clean the gravel with a siphon cylinder, but make sure there is adequate biological buildup remaining to maintain the water chemistry.  I can maintain the pH in the tanks with water changes.  This seems to work very well since my adult Uarus are very healthy and I have gotten over 30 spawns from 2 mated pairs in about 6 months.  One pair spawned so frequently (every 5 or 6 days) that I dropped the temperature to the mid 70s’ to give them a rest!


Spawning Uarus is a challenge but certainly possible.  First of all, make sure you look thoroughly for the eggs!  The eggs are small and clear brownish, very difficult to see in the back of a dimly lit aquarium (I use a 2 bulb shoplight above the tank, but the water sprite growth on the surface is very dense).  My fish probably had spawned 2 or 3 times before I realized it---I could only see the eggs after thoroughly checking with the room lights off and the tank lights on.  There is little courtship display and that is mostly slow and deliberate.  I did see one pair lock jaws and wrestle for the initial pair bonding, but that has not happened since, and they probably mate for life.  The real indication of spawning was that the pair had separated themselves from the other fish in the tank.  The pair was slow and deliberate in protecting their territory, but well respected from observing the tightly concentrated other fish.  Uaru are almost impossible to sex, although the males seem to be larger.  Even the bluntness of the head and the pointing of the anal and dorsal fins seem to be inconclusive.  The best way to get a pair is to obtain 5 or 6 fry and raise them together.  As with other fish, good food and water changes help.  A vertical, angled, or horizontal slate or a large clay pot can be used, although I have even had them clean off to the undergravel plate and lay eggs there!  Yes, they move gravel, much more than many cichlids.  They have piled up gravel 10 inches against the glass and made a depression nearly 2 feet in diameter.  Now you can see why I prefer 2 strong powerhead filters and lots of gravel!  


The spawns have varied in size from 75 to about 200 eggs.  Articles often state that Uaru will usually eat their eggs or fry.  Several times my fish had wiggling fry in a depression in the gravel.  However, only once did I observe free-swimming fry with the parents, and they soon disappeared.  It seems that at least a few would have survived.  The problem may have something to do with the water conditions, because the pairs seemed to be good parents and very protective of their eggs.   The egg hatch rate has been quite good, averaging about 50-60%.  I have found that removing and hatching the eggs artificially can work quite well.  I use a “siphon on a stick” to go into the tank and remove the eggs.  Sometimes I leave half the eggs to see if the parents will succeed in raising the fry, but even though those may hatch and be cared for, they still disappear later.  After rinsing the eggs off, they are placed in rainwater with methylene blue under heavy aeration.

The eggs hatch in 2-3 days and the fry are removed and placed in clean rainwater.  In 5 days the fry are free-swimming.  Heavy aeration seems important to keep the fry circulating in the jar and avoid tightly clumping and getting in a bent condition.  They show amazing ability to handle current.


That brings us to the hardest part---getting the fry to survive.  The fry are very tiny, about the size of apisto fry, with even smaller mouths.  They are constantly moving and picking at everything, seemingly trying to feed, and likely feed off the parents slime as Discus fry do.  I have tried Liquifry, micro powdered dry food, and egg yolk, but have had only limited success with getting the fry to the brine shrimp stage.  It appears that the fry are finicky eaters, water quality must be extremely high, and the food must be moving in front of them (current from aeration).  Even when they begin eating baby brine shrimp, it is difficult to tell since they don’t show the typical orange belly.  When feeding the fry, the tendency is to overfeed, and the pollution kills them.  To keep food in front of the fry, use a small container (e.g. gallon jar), heavy aeration, and change water frequently.  Without heavy aeration, the fry are less active and do not survive as long.  Rain water or water drawn from the parents’ tank seems to be best for them.  Water different in pH and composition should only be added slowly later.  Transferring the fry to larger containers should be done carefully with the same composition water if possible.  Many of the fry perish just before or in the early stages of eating newly hatched brine shrimp.  At about 1 ½ to 2 months the fry become less sensitive to water changes.  I have raised about 150 fry so far, but it is frustrating to have so low a percentage of survival.  Any suggestion from discus breeders would be welcome.


In conclusion, Uaru amphiacanthoides is a graceful, colorful, interesting, and challenging fish to keep and breed.  Because of its’ peaceful nature, it can be kept with many other peaceful South American species of fish.  For those with some experience breeding fish, it can be a top-notch challenge I would highly recommend!