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Peaceful when young but eats smaller fish and plants; needs a huge tank or pond.
87 species in our list are a good match.
Peaceful when young but eats smaller fish and plants; needs a huge tank or pond. Often released illegally.
Check your local laws. This animal is banned or needs a permit in some places, for example several US states. Check the rules where you live before you buy one, and never release it into the wild.
Not for home aquariums. This fish grows far too big for any home tank. It needs a pond-sized system of thousands of litres, so please don't buy one as a baby.
Pellets, fruit and vegetables.
Tap a food to see what it is.
Mature females are a little rounder-bellied than males; juveniles cannot be sexed.
Common problems. Tap one to see the signs. This is a guide, not a diagnosis.
Egg-scatterer ·
Not bred in home aquaria; bred in large numbers for food in South America and Asia, often using hormone-induced spawning.
Needs a school of 6+ in a large tank; ripe females swell with eggs.
Very large tank or pond with floating plants or mops, soft slightly acidic water and warm temperatures.
Rainy-season style water changes with soft, slightly cooler water and plenty of greens and protein.
Very fecund: FishBase gives a fecundity of 7,000-300,000 eggs per female. Sexual maturity at about 60-62 cm, at 7-10 years old in the wild.
Fry take powdered food and brine shrimp nauplii, then chopped greens; grow fast and need space.
A huge Amazon and Orinoco fish (the tambaqui), the second-largest scaled fish of the Amazon, sold as a small "vegetarian piranha" and farmed for food across South America and Asia; outgrown aquarium fish are often released.
Georges Cuvier described the black pacu (tambaqui) in 1816. It is a major food fish across the Amazon and is widely farmed in South America. Juveniles are sometimes sold as aquarium fish, but adults grow far too large for home tanks.
First described by Georges Cuvier in 1816.
17 facts checked with sources
Valid; synonyms include Colossoma nigripinnis/Myletes nigripinnis. Juveniles are confused with Piaractus pacus and red-bellied piranha, and US FWS notes some 'C. macropomum' in Florida may be farmed Colossoma x Piaractus hybrids, so trade fish are not always pure.
Eschmeyer's Catalog of Fishes: species in Colossoma (updated 21 Sep 2026) · FishBase: Colossoma macropomum summaryLegacy has no family. Subfamily Colossomatinae.
FishBase: Colossoma macropomum summarysize-pick: Seriously Fish live-adult figure kept, 60 cm SL (standard length), which it says captive fish easily reach. FishBase max 108 cm TL (total length) is a single IGFA angling record (Ref. 40637), far above aquarium sizes; FishBase common length is 70 cm TL and max published weight 40 kg. Legacy 90 cm is above typical captive adults.
Seriously Fish: Colossoma macropomum (Black Pacu) · FishBase: Colossoma macropomum summaryLegacy has no hardness; Seriously Fish range used, FishBase allows up to 20.
Seriously Fish: Colossoma macropomum (Black Pacu) · FishBase: Colossoma macropomum summary300 x 90 x 90 cm = 2,430 L (Seriously Fish quotes 2,550 L for the imperial size). Legacy 3,000 L is larger and fine as a recommendation.
Seriously Fish: Colossoma macropomum (Black Pacu)Adults are solitary, so one fish is acceptable. Seriously Fish's quick facts say 'needs to be in a group' (juveniles shoal); a group needs an even larger tank.
Seriously Fish: Colossoma macropomum (Black Pacu) · FishBase: Colossoma macropomum summaryWild fish aged from otoliths (Mamoré basin, Bolivia). Legacy '20-25 years' is far too short; no captive lifespan figure found.
Loubens & Panfili 1997, Biologie de Colossoma macropomum dans le bassin du Mamoré, Ichthyol. Explor. Freshwaters 8(1): 1-22 (IRD abstract)'Benthopelagic' is not a tank level. Legacy 'middle' not confirmed.
FishBase: Colossoma macropomum summaryLegacy 2 (moderate) understates it; size alone makes it a difficult aquarium fish.
Seriously Fish: Colossoma macropomum (Black Pacu)Legacy has no range field (story says Amazon).
Eschmeyer's Catalog of Fishes: species in Colossoma (updated 21 Sep 2026) · Seriously Fish: Colossoma macropomum (Black Pacu)Matches legacy (females fuller).
Seriously Fish: Colossoma macropomum (Black Pacu)Wild fish migrate upstream to spawn at the start of the floods (US FWS, Goulding & Carvalho 1982). Legacy breeding guide (school of 6+, mops) is generic and unsourced.
Seriously Fish: Colossoma macropomum (Black Pacu)Legacy 'n/a'. The fecundity figure comes from FishBase's resilience line.
FishBase: Colossoma macropomum summary · Loubens & Panfili 1997, Biologie de Colossoma macropomum dans le bassin du Mamoré, Ichthyol. Explor. Freshwaters 8(1): 1-22 (IRD abstract)Legacy 'grown to over 70 cm' and 'farmed for food across South America and Asia' confirmed. IUCN: Near Threatened (overfishing). LEGAL: Seriously Fish says sale is banned by many US wildlife authorities; check local law. Not on the Texas prohibited list.
Seriously Fish: Colossoma macropomum (Black Pacu) · FishBase: Colossoma macropomum summary · US Fish & Wildlife Service: Tambaquí (Colossoma macropomum) Ecological Risk Screening Summary, 2018