Manuel's Piranha (Serrasalmus manueli)

Meet Manuel's piranha, the green tiger of the Orinoco

Manuel's piranha (Serrasalmus manueli) is a large, deep-bodied piranha from the Amazon and Orinoco river systems of northern Brazil and Venezuela. In the trade it is also sold as the Manny or the green tiger piranha. It is one of the most handsome members of its genus, with a greenish sheen over silver flanks, a bold dark spot behind the gill cover and red marks on the gill cover and lower jaw, and it grows into an impressive, solitary predator.

This page is deliberately frank. Manuel's piranha is a specimen fish for experienced keepers with a very large aquarium. It cannot share a tank with other fish, it needs a tank of its own about two metres long, and it lives for more than ten years. If that suits you, few freshwater fish are as striking. If it does not, our Red-Bellied Piranha and the rest of our centrepiece fish are worth comparing first.

Seriously Fish records the species from the Rio Negro and Rio Xingu and from tributaries such as the Casiquiare, Atabapo and Cunucunuma, in habitats ranging from dense forest to the open Llanos grasslands of Venezuela, where the water is clear, sunlit and full of plants. Adults are usually caught in deep, flowing sections of the main river channels, in both blackwater and clear or white water. FishBase gives the authors as Fernández-Yépez and Ramírez, 1967, and places the species in Serrasalmidae, the piranha and pacu family.

Recognise the species

Those identification points come from Seriously Fish, which also notes that photographs of this fish have been mislabelled in the past and that some geographic forms may one day be described as separate species. The genus has 24 described species and is overdue a full revision. In South America the word piranha belongs properly to Pygocentrus; fish of the genus Serrasalmus go by other names such as pirambeba, and its native name in Venezuela is caribito parguasero. FishBase explains the genus name as Latin for "saw" and "salmon".

Know what you receive

One purchase supplies one live Manuel's piranha. The listing has a single option rather than graded sizes. Seriously Fish notes that adults are rarely available, so expect a young fish, and ask us for the current size before ordering if it affects your plans. Our photographs show the species, not your individual fish: spotting, the amount of red on the throat and the depth of colour vary between fish and change as they grow.

Seriously Fish reports high mortality among imported fish because they are very sensitive to transport, so the first days after arrival matter: have the aquarium ready, cycled and quiet before you order. Our delivery and Live Arrival Guarantee terms explain dispatch days and what to do if anything goes wrong on arrival.

Check this list before you order

Check the UK rules before you buy

Keeping a piranha in a home aquarium is legal in Great Britain, but two pieces of law are worth knowing. First, non-native fish in England and Wales are controlled under the Import of Live Fish Act. The government's guidance links to a checklist of freshwater fish genera that may be kept in indoor aquaria for ornamental purposes under a general licence. The current version (V7, updated 13 October 2026) lists Serrasalmus with no excluded species, so Manuel's piranha may be kept indoors. The licence covers indoor aquaria only, not ponds.

Second, the Schedule of the Dangerous Wild Animals Act 1976, in both its England and Wales and its Scotland versions, lists mammals, birds, reptiles and some spiders and scorpions but no fish, so no dangerous wild animal licence is needed. If you live elsewhere in the UK, check your local rules. Wherever you are, OATA reminds keepers that releasing any aquarium fish into the wild is illegal, and that the Animal Welfare Act 2006 gives every owner a duty of care.

Plan for a 36–44 cm adult and a two-metre aquarium

Sources agree that Manuel's piranha is big, but not on the exact maximum. Both measure standard length, from the snout to the base of the tail, so the full fish is longer.

Seriously Fish describes the species as particularly active and sometimes skittish when its needs are not met, which is why length matters more than height: give it a long run of open water. Use our tank volume calculator to check what your aquarium really holds.

Grow a young fish on with the big tank already planned

A young piranha will not stay small for long. If you start it in a smaller, mature aquarium, have the final tank budgeted, built and cycled before it is needed, because a fish that outgrows its tank becomes stressed, nervous and hard to rehome. OATA's advice for every aggressive species is to buy the largest tank practical for the fully grown fish.

Furnish the tank with wood, sand and shade

Seriously Fish recommends a well-oxygenated aquarium with a sandy floor and large driftwood roots and branches. Cover from the wood helps the fish feel secure and calms it, and dim to moderate lighting suits it better than bright light. Hardy plants such as Vallisneria or Java fern (Microsorum) can be tried, but some members of the genus eat plant matter, so expect nibbled leaves.

Make the layout safe for fish and keeper

Match the water values

Manuel's piranha comes from soft, slightly acidic to neutral rivers, but it does not need extreme water. Seriously Fish notes that wild sites have been measured as low as pH 4.0 and says this does not need to be copied.

UK tap water ranges from very soft to very hard depending on where you live, so test yours or check your water company's report, then compare it with these values in our water matcher. Our water chemistry guide explains pH and hardness, and our tropical tank temperature guide covers heating a large aquarium evenly. Always treat new water with a dechlorinator that removes chlorine and chloramine.

Build filtration for a large, messy predator

A piranha eats rich, meaty food and produces a lot of waste, and Seriously Fish says water quality must be very high. It suggests an external canister filter or a sump, with the return running the length of the tank, and as an example three large filters together giving a turnover of four to five times the tank volume every hour. A spray bar that ripples the surface, plus one or two powerheads, adds oxygen and gentle flow. Our guide to aquarium filtration explains how to size it, and the nitrogen cycle guide explains why the filter must be mature before the fish arrives.

Run a weekly routine

Feed measured meals of dead, meaty foods

In the wild, Manuel's piranha eats the fins and scales of other fish, smaller fish and insects, and occasionally nuts, fruit and seeds. In the aquarium, Seriously Fish says most can be weaned onto dead foods over time; some resist at first, and a short fast can help, especially with larger or newly transported fish.

Choose the right foods

From our range, frozen mussel meat, frozen cockle meat, frozen smelts, large frozen krill and earthworms suit a growing fish, while frozen brine shrimp and frozen Tubifex suit a small one. Seriously Fish warns that piranhas cannot fully process some fats in mammal and bird meat, which can lead to fat deposits and organ damage, and that feeder fish carry a risk of disease and parasites. OATA goes further: live fish must not be used as food.

How often? Seriously Fish feeds adults only two or three times a week; OATA advises feeding aggressive fish no more than once a day. A young, growing fish can take a small meal most days; an adult needs far less. Offer what it eats in a few minutes, use long feeding tongs, and remove leftovers so they do not pollute the water.

Acclimatise it in the dark and leave it alone

Before the fish arrives, check that ammonia and nitrite read zero. OATA's floating-bag method is simple: switch off the aquarium lights, float the sealed bag for 10 minutes so the temperatures match, then add small amounts of tank water to the bag over up to 20 minutes. Net the fish into the tank and throw the bag water away rather than adding it to the aquarium. For a larger fish, OATA describes drip acclimatisation through a thin airline instead. Our guide to acclimatising new fish walks through both.

Keep the lights low for the rest of the day and do not feed until the next day. In the first week, test the water often, keep people away from the glass, and expect a nervous fish that hides in the wood; confidence builds once it learns the routine.

Handle a sharp-toothed fish safely

Seriously Fish notes that piranhas usually bite only when threatened and are not the monsters of films, and FishBase lists the species as harmless, but the teeth are sharp and care is needed during maintenance. OATA advises double-bagging sharp-toothed fish for transport, wearing long-sleeved rubber gloves when working in the tank, washing your hands afterwards and never starting a siphon by mouth. Work with the fish in view, keep your hands out of the water at feeding time, and use a net or container rather than your hands to move it.

Keep it on its own

This is the most important point on the page. OATA's general sheet for aggressive fish says piranhas need groups of at least five, but that advice fits shoaling piranhas such as the Red-Bellied Piranha. For Manuel's piranha, Seriously Fish is clear: it is not gregarious, it is a poor tank mate for other species and needs a tank of its own, and if two or more are kept together the adults fight until only one remains.

Decide with this table

If you want a group of characins in a big South American aquarium, look instead at the Silver Dollar or Red-Bellied Pacu, relatives in the same family, or the Gar Characin, all in our South American characins range. Never add them to the piranha's tank. Our stocking calculator helps plan a separate aquarium.

Watch for health problems early

A healthy fish has clear, bright eyes, intact fins and scales, steady breathing and a good appetite. These warning signs follow OATA's guidance:

Most problems in large predators start with water quality, so the first response is almost always a test and a partial water change.

Understand sexing, breeding and lifespan

Seriously Fish records no external differences between males and females, and the species, like most of its genus, has not been bred in captivity, so we do not give a breeding method. Most piranhas live for more than ten years and become less active with age. FishBase lists Manuel's piranha as Least Concern on the IUCN Red List (assessed 2020). Explore more large, unusual species in our rare and collector fish collection.

Answer Manuel's piranha buying questions

What is Manuel's piranha?

It is Serrasalmus manueli, a large South American piranha from the Amazon and Orinoco basins in northern Brazil and Venezuela. The trade also calls it Manny or the green tiger piranha. It has a greenish sheen, a clear dark shoulder spot and red marks on the gill cover and lower jaw, and it is a solitary fish rather than a shoaling one.

How big does Manuel's piranha grow?

Large. FishBase records 36 cm standard length and 2.5 kg, and Seriously Fish gives 43.5 cm standard length. Standard length leaves out the tail, so a full-grown fish is longer still. Plan the aquarium around the adult, not the size that arrives.

What size aquarium does it need?

Seriously Fish recommends a base of 210 x 75 cm, about 1,181 litres, and a tank at least two metres long. It needs a big external filter or sump, a guarded or external heater and a secure lid.

Can I keep Manuel's piranha in a group or with other fish?

No. Seriously Fish says it is not gregarious, needs a tank of its own and that adults kept together fight until only one remains. OATA's general advice of five or more applies to shoaling piranhas such as the Red-Bellied Piranha, not to this species.

Is it legal to keep a piranha in the UK?

Yes, in an indoor aquarium. The genus Serrasalmus is on the government checklist of freshwater fish that may be kept in indoor aquaria in England and Wales under the general licence, and the Dangerous Wild Animals Act 1976 lists no fish. Outdoor ponds are not covered, and releasing any aquarium fish is illegal.

Will it bite?

Seriously Fish notes that piranhas usually bite only when they feel threatened, and FishBase lists the species as harmless, but the teeth are sharp. Never put your hands in the tank while it is feeding, use long tongs and long gloves for maintenance, and never siphon by mouth.

What does it eat and how often?

Dead meaty foods: mussels, cockles, prawns, chopped squid, whitebait and earthworms for adults, and bloodworm, brine shrimp, Tubifex and chopped prawn for juveniles. Seriously Fish feeds adults two or three times a week. Never feed live fish; OATA advises against it.

What size fish will I receive?

One live fish per purchase. The listing has a single option rather than graded sizes, and adults are rarely imported, so expect a young fish. Ask us for the current size before ordering if it matters for your set-up.

Consult the care references

• Seriously Fish: Serrasalmus manueli: trade and native names, range in the Amazon and Orinoco basins, habitats, maximum length, aquarium size, decor, water values, filtration, diet, weaning onto dead foods, why it is kept alone, identification, transport sensitivity and lifespan.
• FishBase: Serrasalmus manueli: author and year, family, distribution, maximum standard length and weight, and IUCN Least Concern status (2020).
• Seriously Fish: Pygocentrus nattereri: the Red-Bellied Piranha for comparison: maximum length, aquarium size and group behaviour.
• OATA: How to look after aggressive fish: UK care sheet for aggressive fish, including piranhas: water-quality limits, maintenance, feeding, the ban on live fish as food, group sizes, handling, acclimatisation and health signs.
• gov.uk: Introduce or keep non-native fish and shellfish: UK government guidance on keeping non-native fish, updated 15 October 2026.
• gov.uk: Freshwater fish that can be kept for ornamental, scientific research or conservation purposes (checklist V7): the government checklist of freshwater fish genera that may be kept in indoor aquaria in England and Wales under the general licence (V7, last updated 13 October 2026).
• legislation.gov.uk: Dangerous Wild Animals Act 1976, Schedule: the Schedule of the Dangerous Wild Animals Act 1976 (England and Wales, and Scotland versions), which lists no fish.
• Tropical Fish Co delivery policy: current dispatch days and Live Arrival Guarantee terms.