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No federal permit to keepMonoculus Peacock Bass
Cichla monoculus
Fishes › Cichlids (Cichliformes) › Cichlidae (Cichlids)
Cichla monoculus, sometimes known as the tucanare peacock bass ("peacock bass" is also used for some of its relatives) or toukounaré, is a very large species of cichlid, and a prized game fish.
Care at a glance
Species-specific aquarium care
- Tank: At least 138 in long and 54 in front to back for one adult (adults commonly reach about 27.6 in / 70 cm).
- Water: Freshwater.
- Temperature: 77–82°F (range recorded for this species).
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
- Availability: Mostly kept by public aquariums; private keeping is uncommon.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 77–82 °F, pH 6.5–7.5, 0–15 dGH.
- Behaviour: temperament territorial.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “This species requires a lot of swimming space, so it is a good idea to furnish the tank fairly sparsely.”
- Tankmates: “Territorial and moderately aggressive.”
- Breeding: “Limited reports of breeding in the hobby.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Oscars, peacock bass, pike cichlids and eartheaters
Applies to most species in this group. Habitat: Large South American rivers. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For one adult Astronotus ocellatus, plan at least a 150 × 60 cm base according to Seriously Fish; pairs and groups need more space. Use separate adult plans for Cichla and each eartheater species.
- Soft sand for eartheaters (Geophagus, Satanoperca), which sift substrate through their gills.
Climate & lighting
Starting point only: The blanket warm-water interval excludes the subtropical seasonal requirements of G. balzanii; use overrides. Check the species-specific values for this animal where shown.
| Water | 77–84°F |
Diet
- Astronotus ocellatus is an omnivore with a preference for animal foods; offer quality pellets and varied suitable foods rather than feeder-fish dependence. Cichla and substrate-sifting eartheaters require separate feeding plans.
Health watch
- Hole-in-the-head disease and lateral line erosion in poor water; eartheaters suffer on sharp gravel.
Understanding the animal
About this animal
About this animal
It is native to the Amazon basin in South America, but has also been introduced to regions outside its natural range (e.g., Florida and Hawaii). It reaches 80 cm (31 in) in length and 9 kg (20 lb) in weight.
Quoted from the Wikipedia article “Cichla monoculus” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams. Uses both the bottom and open water. Specimens collected were from flood prone areas, but in the Amazon the biotopes are more varied. This fish forays along the shore where small fishes may be concentrated. Juveniles feed on shrimps, while adults are almost exclusively piscivore. Oviparous. |
| Water it lives in | Freshwater, 77–82 °F (25–28 °C), pH 7. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: nesters. |
What this means for care
- Keep water within its wild range, 77–82 °F.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 90°F (up to 93°F in the hottest sampled areas) |
| Cool-season lows | about 69°F (down to 59°F in the coldest sampled areas) |
| Average temperature | 74–81°F across sampled records |
| Relative humidity | 78–84% on average (driest month about 76%) |
| Rainfall | about 2209 mm a year |
Measured at 287 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | Cichla monoculus, sometimes known as the tucanare peacock bass ("peacock bass" is also used for some of its relatives) or toukounaré, is a very large species of cichlid, and a prized game fish. It is native to the Amazon basin in South America, but has also been introduced to regions outside its natural range (e.g., Florida and Hawaii). It reaches 80 cm in length and 9 kg in weight. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Reproduction | May spawn 3-4 times a year in batches of 50 to 100 eggs, each spawning lasting 2-3 hours. — FishBase |
| Appearance and size | Maximum length 70.0 cm sl male/unsexed; maximum published weight 9.0 kg. — FishBase |
| Biology | Specimens collected were from flood prone areas, but in the Amazon the biotopes are more varied. This fish forays along the shore where small fishes may be concentrated. Juveniles feed on shrimps, while adults are almost exclusively piscivore. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Typical adult weight
Average adult body mass in each database (FishBase gives the maximum recorded weight).
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
pH
Water hardness
Veterinary & husbandry research
Veterinary & husbandry research
- Infestation by Ergasilus coatiarus (Copepoda: Ergasilidae) in two Amazonian cichlids with new host record from Peru: An ectoparasites natural control approach Mathews PD et al., Comptes rendus biologies 2018
Peer-reviewed papers that mention this species alongside captivity, zoos, veterinary care or aquaculture. Some cover several species or mention it only in passing, so check the abstract. 170
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Seriously Fish: Gymnogeophagus balzanii Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Astronotus ocellatus Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- PubMed (U.S. National Library of Medicine) Peer-reviewed researchIndex of peer-reviewed veterinary, zoo and husbandry research.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
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