---
type: species
title: "Silver Arowana Care: The Ultimate Guide to the Water Dragon"
slug: "silver-arowana"
category: "freshwater"
scientificName: "Osteoglossum bicirrhosum"
subcategory: "Freshwater Oddball"
lastUpdated: "2026-04-26"
readingTime: 12
url: https://www.fishstores.org/species/silver-arowana
---

# Silver Arowana Care: The Ultimate Guide to the Water Dragon

*Osteoglossum bicirrhosum*

Master Silver Arowana care. Learn about the massive tank requirements (250+ gal), preventing Drop Eye, feeding tips, and choosing the best tank mates.

## Species Overview

The silver arowana (*Osteoglossum bicirrhosum*) is the fish that turned a generation of hobbyists into "monster fish" keepers. Sometimes called the Water Dragon for the way its long, ribbon-like body undulates just below the surface, this Amazonian predator is one of the most recognizable freshwater giants in the hobby — and one of the most consistently mis-sold. The juvenile you see in a 20-gallon retail display is, on average, eight months from outgrowing a 75-gallon tank and roughly two years from outgrowing anything most homes can reasonably accommodate.

Silver arowanas are bony-tongued fish (family Osteoglossidae), an ancient lineage whose lineage traces back over 150 million years. They are surface specialists with an upturned mouth designed to inhale insects, fish, and even small birds that fall from overhanging vegetation. In the wild they routinely exceed 3 feet, and unverified reports place wild specimens past 4 feet. None of that is theoretical when you bring one home — these fish grow at a rate that punishes hobbyists who underbuy on tank capacity.

| Field       | Value                      |
| ----------- | -------------------------- |
| Adult size  | 30-36 in (76-91 cm)        |
| Lifespan    | 10-15 years                |
| Min tank    | 250 gallons                |
| Temperament | Aggressive predator        |
| Difficulty  | Advanced                   |
| Diet        | Carnivore (surface feeder) |

### The Water Dragon Morphology and Barbels

The silver arowana's body plan is purpose-built for surface ambush. The mouth tilts almost vertically upward, forming a near-90-degree hinge that opens like a drawbridge. A pair of fleshy barbels extends from the lower jaw — sensory organs used to detect surface vibrations and movement of prey on or just above the waterline. The dorsal and anal fins fuse into a long, continuous ribbon along the rear two-thirds of the body, propelling the fish with the slow, sinuous undulation that earned the Water Dragon nickname.

Their iridescent silver scales are massive — some of the largest of any freshwater fish — and arranged in a mosaic that catches light from below as the fish patrols the surface. Juveniles still carry a yellow-orange tag near the anal fin, a vestige of the yolk sac, which fades by the time the fish reaches roughly 8 inches.

### Natural Habitat: The Amazon River Basin

Silver arowanas inhabit the slow backwaters, flooded forests (varzea), and oxbow lakes of the Amazon and Essequibo basins across Brazil, Peru, Colombia, Guyana, and French Guiana. During the wet season, when river levels rise 30 feet or more, arowanas swim into the flooded jungle and hunt insects, spiders, and small vertebrates among the submerged tree branches. Their famous jumping ability is not a quirk — it is a primary feeding strategy. Documented leaps of 6 feet out of the water to snatch beetles or roosting birds are routine.

Native water is soft, warm (78-86°F seasonally), and stained brown by tannins. pH typically sits between 5.5 and 6.8. None of this means you need to recreate blackwater conditions in captivity, but it does mean the fish is built for warm, soft, slightly acidic water — and is unforgiving of the high-pH, hard-water swings that come with neglected large-tank water changes.

### Growth Rate: From 4-inch Juvenile to 3-foot Giant

This is the single fact most prospective owners underestimate. A 4-inch juvenile arowana can hit 12 inches inside six months and clear 24 inches by the end of year one with proper feeding. Growth slows after roughly 18 months but does not stop — a healthy captive will continue adding length and girth into year three before plateauing somewhere between 30 and 36 inches.

The implication is brutal: any tank under 180 gallons is a temporary holding facility, not a home. If you cannot commit to a 250-gallon-plus permanent setup before the fish arrives, do not buy it. The rehoming market for adult arowanas is small and increasingly saturated, and stunted fish develop spinal deformities and shortened lifespans.

> **The fish will outgrow your tank faster than you can save for a bigger one**
>
> Hobbyists routinely buy a 6-inch juvenile in a 75-gallon tank, plan to "upgrade soon," and run out of runway by month nine. Build the 250+ gallon setup first. If the budget or floor space isn't there now, it won't be there in ten months either — choose a different species.

## Water Parameters & Tank Requirements

Adult silver arowanas need length and width far more than depth. Their entire life happens in the top 12 inches of the water column, so a tall reef-style tank is wasted on them. The footprint is what matters: enough horizontal swimming room to cruise, enough width to make a turn, and enough surface area for gas exchange given their high oxygen demand.

### Minimum Tank Size: Why a 6-Foot Length Is Just the Start (250+ gallons)

For a single adult, 250 gallons is the floor. A 96 in × 30 in × 24 in (8-foot) tank at roughly 300 gallons is the practical sweet spot, and serious keepers go to 450-600 gallons (10-12 foot custom builds) without anyone questioning the decision. Width is non-negotiable: at least 30 inches across. An arowana cannot turn around in a 24-inch-wide tank without scraping its barbels and rostral region against the glass, and chronic abrasion leads to barbel loss, mouth deformities, and a permanently bent spine in extreme cases.

Depth above 30 inches is wasted — the fish lives at the surface. Length and width win every time.

### The Importance of a Weighted, Tight-Fitting Lid (Jumping Hazards)

Carpet surfing is the leading cause of premature death in captive arowanas. They jump. They jump hard, they jump from a near-stationary start, and a startled adult can launch a glass canopy clean off a 250-gallon tank. A weighted lid is mandatory — not "recommended," not "a good idea," but the difference between a living fish and a dried-out body on the floor at 3 a.m.

Use a custom-cut polycarbonate or thick acrylic top with cinder blocks, dive weights, or steel bars holding it down. Mesh screen tops alone will not stop a 25-pound fish. Cover every gap, including filter cutouts and feeding hatches. Many keepers add interior egg-crate baffles below the lid as a secondary catch.

> **Most arowana deaths happen on the carpet, not in the tank**
>
> A glass canopy that "feels heavy enough" is not heavy enough. A 30-inch fish moving from a dead stop can generate enough vertical force to launch unweighted lids across the room. Add weight until the lid does not budge when you push up from underneath with two hands.

### Water Chemistry: Soft, Acidic Water (pH 6.0-7.0) and 75-82°F

Arowanas tolerate a fairly wide pH range (6.0-7.5) but thrive in the soft, slightly acidic end of the spectrum. Hardness should sit at 4-12 dGH. Temperature wants to stay in the 75-82°F band — most keepers hold 78-80°F year-round. Stable matters more than perfect. Wild swings stress the fish and trigger immune crashes.

Ammonia and nitrite must be zero, full stop. Nitrate should stay under 20 ppm. Adult arowanas are notably nitrate-sensitive, and chronic exposure above 40 ppm contributes to fin erosion, lethargy, and the eye and barbel issues this species is prone to. Plan on 30-50% weekly water changes minimum on a fully stocked adult tank, and treat that as the floor, not the ceiling.

For sizing the cycle on a tank this large before adding a high-bioload fish, work through our [aquarium dimensions guide](/guides/aquarium-dimensions) when planning the build.

### Filtration Needs: Managing High Bioload with Sumps and FX6/FX4 Canisters

A surface-feeding carnivore that accepts 6-12 inch food items produces serious waste. Single-canister setups will not cut it past juvenile stage. The two practical filtration approaches:

- **Sump-based filtration** is the gold standard for tanks 250 gallons and up. A 75-100 gallon sump with mechanical pre-filtration, a packed bio-chamber (Marine Pure blocks, ceramic noodles, or bioballs), and a refugium for chemical filtration handles the bioload of a single adult arowana plus tank mates with room to spare.
- **Stacked canisters** — typically two Fluval FX6 units, or an FX6 paired with an FX4 — are the alternative for keepers who can't plumb a sump. Plan for 8-10x tank turnover per hour total flow when stocking heavy.

Surface agitation matters specifically for arowanas. They breathe at the surface and benefit from strong gas exchange. Add powerheads angled along the surface, or use a sump return that breaks the waterline.

## Diet & Feeding

Silver arowanas are obligate carnivores with one of the most specialized feeding niches in the hobby: surface-only. Anything that sinks past the first few inches is generally ignored. Train your fish on floating foods early.

### High-Protein Staples: Pellets, Krill, and Silversides

The modern, healthy arowana diet leans heavily on premium floating carnivore pellets (Hikari Massivore, NLS Thera+A Large, Saki-Hikari) supplemented with frozen and freeze-dried whole prey items. The rotation that produces the best growth and color:

- Floating carnivore pellets (50-60% of diet) — a balanced base with proper vitamin and mineral fortification.
- Krill, shrimp, silversides, and smelt (25-35%) — frozen, thawed, and surface-fed. Whole prey items provide carotenoids that intensify scale color.
- Earthworms and mealworms (10-15%) — gut-loaded, in moderation. High in fat, so don't overdo it.
- Crickets and roaches, gut-loaded (occasional treat) — closest analog to wild diet.

Feed juveniles 2-3 times daily, adults once daily or every other day. Adults are prone to obesity and fatty liver disease from overfeeding, which contributes directly to Drop Eye.

### The Danger of Live Feeders: Parasites and Nutritional Deficiencies

The "feeder goldfish" pipeline is the single biggest avoidable killer of pet arowanas. Feeder fish from low-end pet stores arrive carrying ich, internal parasites, fish tuberculosis, and viral pathogens. Goldfish in particular contain thiaminase (which destroys vitamin B1) and high fat content that drives liver disease and Drop Eye when fed long-term. There is no responsible way to feed pet-store goldfish to your arowana.

If you want to feed live food for enrichment, gut-load your own crickets, roaches, mealworms, and earthworms. Captive-bred guppies or convict fry from your own breeding tank are an acceptable occasional treat. Anything purchased from a feeder tank is a parasite vector — full stop.

> **Goldfish are the fastest path to Drop Eye and fatty liver**
>
> Thiaminase plus high fat plus parasite load makes feeder goldfish actively harmful as a staple. Hobbyists who switched their adults from goldfish to high-quality pellets and frozen krill report eye improvements, better color, and renewed activity within 8-12 weeks.

### Surface Feeding Habits and Training to Take Floating Food

Juveniles will hit anything that wiggles at the surface. Use that window to imprint pellets. Drop a few floating pellets among the live or frozen food the fish already accepts, and over 2-4 weeks shift the ratio toward pellets. By the time the fish hits 12 inches, pellets should be the easy default. Adults that were started on live feeders are notoriously stubborn about converting later, which is why getting the early diet right matters so much.

A daily target zone helps — feed at the same end of the tank, at the same time of day. Many keepers train their arowana to take pellets from a long feeding stick or even from their fingers (mind the teeth on adults).

## Tank Mates & Compatibility

The arowana lives in the top inch of the tank. Anything that occupies the same surface lane is a fight; anything that gets eaten is food. The compatibility math is straightforward: pick fish that are big enough not to be inhaled, occupy a different layer of the water column, and aren't aggressive enough to nip an arowana's long anal fin.

### Selecting Large Bottom-Dwellers (Bichirs, Rays, and Large Plecos)

The classic arowana tank is built in three layers. Bottom dwellers fill the floor and rarely interact with the surface specialist above:

- **Bichirs** — [endlicheri bichirs](/species/endlicheri-bichir), [delhezi bichirs](/species/delhezi-bichir), [ornate bichirs](/species/ornate-bichir), and [senegal bichirs](/species/senegal-bichir) all work well. They occupy the substrate, ignore the arowana entirely, and can take food the arowana misses.
- **Freshwater stingrays** — [motoro stingrays](/species/motoro-stingray) and [black diamond stingrays](/species/black-diamond-stingray) make stunning bottom companions in 300+ gallon tanks but require pristine water and skilled keepers.
- **Large plecos** — [common plecos](/species/common-pleco), [sailfin plecos](/species/sailfin-pleco), [royal plecos](/species/royal-pleco), and [gold nugget plecos](/species/gold-nugget-pleco) clean glass and ignore the arowana.
- **Large catfish** — [striped raphael catfish](/species/striped-raphael-catfish) and [tiger shovelnose catfish](/species/tiger-shovelnose-catfish) work in proportionally large tanks.

### Mid-Water Companions: Oscars, Datnoids, and Large Cichlids

Mid-water tank mates need to be assertive enough not to be bullied but not so aggressive that they nip the arowana's fins. The reliable picks:

- [Tiger oscars](/species/tiger-oscar), [red oscars](/species/red-oscar), and [albino oscars](/species/albino-oscar) — the textbook mid-water companion. Both species are messy eaters, so plan filtration accordingly.
- [Green terrors](/species/green-terror), [jack dempseys](/species/jack-dempsey), and [red devil cichlids](/species/red-devil-cichlid) — possible but personality-dependent. Watch for fin-nipping.
- [Clown knifefish](/species/clown-knifefish) and [black ghost knifefish](/species/black-ghost-knifefish) — large, peaceful, and occupy the mid-bottom layer.
- [Tinfoil barbs](/species/tinfoil-barb) and [bala sharks](/species/bala-shark) — fast, large schooling fish that fill the middle column without provoking the arowana.

### Species to Avoid: Small Community Fish and Aggressive Fin-Nippers

Anything under 6 inches is potential food. That means [neon tetras](/species/neon-tetra), guppies, [harlequin rasboras](/species/harlequin-rasbora), and similar community staples are off the table — they will be inhaled within days. Avoid notorious fin-nippers ([tiger barbs](/species/tiger-barb), [serpae tetras](/species/serpae-tetra)) which will harass the arowana's long, flowing fins. Also skip surface specialists like hatchetfish — they compete for the same swimming lane.

Other arowanas are usually a no-go. Two adult silver arowanas in the same tank almost always end in death for one of them unless you're running a 500+ gallon system designed specifically for a pair. The same applies to adding an [asian arowana](/species/asian-arowana), [black arowana](/species/black-arowana), or [jardini arowana](/species/jardini-arowana) to a tank with an existing silver — territorial aggression at the surface is fatal.

## Common Health Issues

Most arowana health problems trace back to two root causes: tank dimensions that are too small, and a diet too heavy on fatty live foods. Get those two right and the species is surprisingly hardy. Get them wrong and you'll spend years fighting Drop Eye, spinal curvature, and recurring head trauma.

### Drop Eye (Ptosis): Causes, Prevention, and Myth-Busting

Drop Eye is the signature ailment of captive arowanas. The eyeball rotates downward in the socket, leaving the fish with a permanent "looking down" stare. It's almost never fully reversible once it sets in — prevention is the only real cure.

The accepted contributing factors:

- **Excess body fat** — fatty deposits behind the eye push the eyeball forward and down. Diet rich in goldfish, beef heart, or other high-fat foods is the most common culprit.
- **Constantly looking downward** — fish housed where the only points of interest are below the surface (substrate-level tank mates, food sinking to the bottom) develop the muscle pattern. Surface-level enrichment helps.
- **Genetics** — some specimens are predisposed regardless of care.

Prevention: floating pellets and frozen surface food, lean diet, no goldfish, regular water changes to control nitrate, and visual interest at the surface (floating plants, drifting cork bark).

### Jump Injuries and Head Trauma

A spooked arowana strikes the lid hard enough to bruise the rostral region, dislodge scales, and in worst cases break its spine. Lid weight is one half of the prevention equation — the other half is reducing startle triggers. Don't approach the tank suddenly. Avoid bright reflections off the inside of glass canopies. Keep room lighting consistent rather than flicking lights on and off.

Recurring jumps suggest a problem: poor water quality, an unsuitable tank mate harassing from below, or insufficient surface coverage that makes the fish feel exposed. Diagnose the trigger rather than just adding more weight to the lid.

### Ammonia Burn and Nitrate Sensitivity in Large Specimens

Adult arowanas in undersized or under-filtered tanks frequently show fin erosion, mucus stripping, and reddened gill plates — all signs of chronic exposure to elevated ammonia, nitrite, or nitrate. The fix is not medication; it's filtration capacity and water-change schedule.

Test water weekly at minimum. Treat any nitrate reading above 20 ppm as a signal to do a 50% change, and any detectable ammonia or nitrite as an emergency. For tanks of this size, an automated water-change system pays for itself in hours saved within the first year.

> **Track nitrate, not just ammonia**
>
> Most established arowana tanks pass ammonia and nitrite tests easily — the silent killer is creeping nitrate from heavy feedings. Logging weekly nitrate readings catches filtration drift before the fish starts showing symptoms.

## Where to Buy & What to Look For

Silver arowanas are widely available — and widely sold to people who shouldn't own them. The retail price of a 4-6 inch juvenile is misleadingly low ($30-80), which is why so many end up in undersized tanks. Pick your specimen carefully. A bad start at the LFS is hard to undo.

### Assessing Juvenile Health: Alertness and Fin Integrity

A healthy juvenile arowana should hold position calmly near the surface, with extended dorsal and anal fins, both barbels intact and pointing forward, both eyes tracking movement uniformly, and no white film on the body or fins. It should respond to your finger near the glass — predators are curious by nature.

Skip any fish with:

- Curled, missing, or bent barbels — sign of cramped quarters or rough handling.
- Asymmetric eyes or any sign of one eye drifting downward — early Drop Eye is a permanent strike.
- Clamped fins, sluggish surface posture, or hanging at an angle — almost always indicates internal disease or recent shipping stress.
- Visible jaw deformity or upturned "underbite" worse than the natural arowana profile — caused by surface impact or poor early growth.
- Scales missing in patches, especially around the head — fight injuries or jump trauma.

### Buyer Checklist

- [ ] Both barbels present, straight, and pointing forward
- [ ] Eyes symmetric with no downward rotation
- [ ] Dorsal and anal fins fully extended, no clamping
- [ ] Active surface posture, responsive to movement
- [ ] Clean iridescent scales with no missing patches
- [ ] Juvenile is at least 4 inches long (smaller fry have very high losses)
- [ ] Store tank is at least 75 gallons with a secure, weighted lid
- [ ] Store can name the fish's diet and age — refuses if they cannot

### Ethical Sourcing and Transporting a Large Fish

The unique angle worth taking seriously: when you walk into a local fish store to buy a juvenile silver arowana, you are evaluating the store as much as the fish. A store that holds a 6-inch arowana in a 20-gallon retail cube has already stunted the specimen's growth potential — pass on it regardless of how the fish looks. A responsible store keeps juveniles in tanks of 75 gallons or larger, with a covered, weighted lid, in groups of two to four max, and is willing to talk specifically about feeding history and source.

Ask three questions before buying:

1. What is this fish currently eating, and how often?
2. How long has it been in this tank, and what was its size at intake?
3. Who is the wholesaler or breeder, and is this a wild-caught or captive-bred specimen?

Captive-bred Brazilian or Asian-farmed arowanas are widely available and significantly hardier than wild-caught fish, which arrive stressed and parasitized. The price difference is small relative to the long-term success rate.

> **Buy juveniles in person, not online**
>
> Shipping a 4-6 inch arowana is high-stress and high-risk — the fish that survives the box often spends weeks recovering. Local pickup lets you inspect the fish, weigh the lid on the holding tank, and evaluate the store's husbandry firsthand. For a fish that will live with you for 10-15 years, the in-person purchase is worth the drive.

For transport, double-bag the fish with at least 2/3 of the bag as oxygen, cushion it inside an insulated box, and minimize travel time to under 4 hours when possible. Acclimate slowly using the drip method — work through our [how to acclimate fish](/guides/how-to-acclimate-fish) guide for the protocol — and dim the lights for the first 24-48 hours after the fish enters its new home.

## Quick-Reference Cheat Sheet

| Parameter         | Target                                                | Notes                                         |
| ----------------- | ----------------------------------------------------- | --------------------------------------------- |
| Adult size        | 30-36 in (76-91 cm)                                   | Wild specimens to 4 ft                        |
| Lifespan          | 10-15 years                                           | Up to 20 with optimal care                    |
| Minimum tank      | 250 gallons                                           | 300-400 gal preferred, 30+ in width mandatory |
| Tank length       | 8 ft minimum                                          | Length and width matter more than depth       |
| Temperature       | 75-82°F                                               | Hold 78-80°F year-round                       |
| pH                | 6.0-7.5                                               | 6.0-7.0 ideal for color and longevity         |
| Hardness          | 4-12 dGH                                              | Soft, slightly acidic water preferred         |
| Nitrate ceiling   | Under 20 ppm                                          | Highly nitrate-sensitive as adult             |
| Diet              | Floating carnivore pellets + frozen krill/silversides | Avoid feeder goldfish entirely                |
| Feeding frequency | 1x daily adult, 2-3x daily juvenile                   | Prone to obesity and Drop Eye                 |
| Lid requirement   | Weighted, fully sealed                                | Carpet surfing is the #1 killer               |
| Filtration        | Sump or stacked FX6/FX4 canisters                     | 8-10x turnover per hour                       |
| Tank mates        | Bichirs, large plecos, oscars, knifefish              | Nothing under 6 inches                        |
| Difficulty        | Advanced                                              | Space and budget commitment, not technique    |
| Growth rate       | 2 in/month in year 1                                  | Plan tank capacity before purchase            |

## Frequently Asked Questions

### How big do Silver Arowanas get in captivity?

While they can reach 4 feet in the wild, most home-aquarium Silver Arowanas top out between 30 and 36 inches. Growth is extremely rapid in the first year, often exceeding 2 inches per month.

### What size tank does a full-grown Silver Arowana need?

A single adult requires a minimum of 250 gallons, but a 300-400 gallon tank with a wide footprint (at least 30 inches wide) is preferred to allow the fish to turn around comfortably without spinal deformities.

### Can Silver Arowanas live with Oscars?

Yes, Oscars are common tank mates as they occupy the middle/bottom of the tank while the Arowana stays at the surface. However, both are messy eaters, so over-filtration is mandatory for this pairing.

### Why does my Arowana keep jumping against the lid?

Arowanas are natural predators that jump for insects in the wild. In a tank, they may jump due to being startled, poor water quality, or seeing reflections. A heavy, secure lid is the only way to prevent fatal carpet surfing.

### How do I prevent Drop Eye in my Arowana?

While genetics play a role, you can minimize risk by avoiding fatty live foods, keeping the fish from looking down at bottom-dwellers constantly, and ensuring high water quality to prevent fatty deposits behind the eye.

---
*Source: [FishStores.org](https://www.fishstores.org/species/silver-arowana)*
*Last updated: April 26, 2026*