Arowana & Gar

Drop eye

SignsOne or both eyes point downward and do not return. Common in silver arowana; caused by fat deposits around the eyeball

PreventionReduce sinking food and the habit of searching the bottom for food. Avoid high-fat food and darken the tank sides

Gill curl

SignsEdge of the gill cover curls outward and breathing speeds up. Exposed gills are easily injured

PreventionCaused by a cramped tank, insufficient water changes or high temperature. Prevent with ample space and weekly water changes

White spot (ich) / parasites

SignsWhite spots on the body or fins, rubbing against objects, clamped fins, rapid breathing

PreventionAvoid sudden temperature changes; quarantine new live food or fish in a separate tank for 2 weeks before adding

Refusal to eat / indigestion

SignsSees food but will not open its mouth, spits it out, swollen belly, white thin feces

PreventionDo not feed only one type of food. Avoid too much large live food or insects, and prevent low water temperature

Aeromonas infection

SignsRed spots or bleeding on the body, raised scales (pinecone), belly swollen with fluid, ulcers

PreventionCaused by poor water quality, overcrowding and leftover food. Strengthen filtration and keep nitrite at zero

Fin rot / tail rot

SignsFin edges turn cloudy white and shorten as if melting. Split tail fin does not knit back together

PreventionSet up the tank so fins are not injured by jumping or hitting walls. If injured, keep water quality at its best

Jumping out / falling

PreventionLid must cover the entire tank with a weight or lock. Avoid sudden flashing of lights and tapping the tank

First aidReturn to the tank quickly with wet hands or a towel. Even if dried out, do not give up; return it and aerate. Record injuries and see the vet

Mouth / jaw injury

PreventionCaused by hitting the lid or walls. Provide a tank depth of 60 cm or more and do not startle. Pad the inside of the lid

First aidIf the jaw will not close or the fish cannot eat, suspect a fracture. Keep water quality at its best and see the vet the same day. Do not handle

Lost scales / skin lacerations

PreventionReduce sharp edges on driftwood and rocks. Avoid fights with tankmates; move with a container, not a net

First aidLeave it alone and keep water quality at its best with water changes. Cloudy white or red swelling means infection. See the vet within a few days

Gar snout injury

PreventionGar easily bumps its long snout on walls. Give enough tank length and dim the lights gradually

First aidSee the vet if bleeding continues or the snout is bent. White cottony growth on the wound suggests fungus. Manage water quality strictly

Nontuberculous mycobacterial infection

RouteSmall cuts on hands that touch tank water or fish

PreventionWear rubber gloves if you have hand wounds. Wash with soap after work. See a doctor if skin swelling persists

Aeromonas infection

RouteTank water, fish body surface or bite wounds into open cuts

PreventionAvoid bare-handed work; rinse bite wounds under running water and disinfect. See a doctor for swelling or fever

Salmonellosis

RouteHands that touched tank water, live food or equipment, then the mouth

PreventionDo not wash equipment in the kitchen. Wash hands after work. Handle live food with dedicated containers and tools

Gar egg poisoning

RouteEating gar eggs (toxic to humans)

PreventionNever eat the eggs and keep children from touching them. If spawning occurs, collect with gloves and dispose

Food

• Commercial food for large fish as the staple. Juveniles twice a day, adults once every 1–2 days
• Frozen shrimp, crickets, bloodworms etc. as supplements. Do not let arowana depend on live food
• Remove leftovers right away. One fasting day a week to rest the organs

Water

• Water 26–30°C, pH 6.5–7.5 (slightly acidic to neutral). Dechlorination is essential
• Nitrite 0, nitrate low. Change 1/3 weekly with a temperature difference within 2°C

Toys & play

• Feed with tweezers or floating food to bring out surface-feeding behavior
• Create a gentle current to encourage swimming and build condition
• Watching from outside the tank is stimulation. Do not startle with sudden movements

Nest, bed & hideout

• No hiding place needed, but darkening one side calms the fish
• Gar likes to rest under floating plants. Add a few floating leaves at the surface

Bedding & litter

• Bare tank or a thin layer of substrate. Thick sand traps dirt
• In arowana, pecking at the bottom leads to drop eye. Keep sand thin
• Gar breathes air with its swim bladder; keep an air gap between the surface and the lid

Cage / housing material

Glass or acrylic. Acrylic is light and suits large tanks but scratches easily

Size & space

Adult arowana: at least 180×60×60 cm. Gar may need over 2 m depending on species

Layout

• Lid covers the whole tank with a weight or lock. Completely prevent jumping out
• Filtration rated for at least 3 times the water volume. Always combine with aeration
• Two heaters with guards. Prepare for burns and failures

Placement notes

• Water weighs over 500 kg. Check floor reinforcement and level
• Avoid direct sunlight and vibration; keep a battery for power outages nearby

Exercise, free-roam & walks

• No walks needed. Tank length determines exercise
• Upgrade the tank as the fish grows. A cramped tank bends the spine
• Move outside the tank in a large plastic bag or container. Nets damage scales

Temperature & humidity

Temperature26–30°C. Below 24°C: refusal to eat and disease; above 32°C: oxygen shortage

HumidityRoom humidity affects condensation on the tank. Do not let condensation on the lid damage the lights

Summer & winter

• Summer: above 32°C, use a cooling fan or chiller. Increase aeration
• Winter: two heaters and insulation. In a power outage, insulate with polystyrene foam

Nail trimming

No nail trimming. Instead, test water weekly (nitrite, nitrate, pH)

Brushing, skin & coat care

Check scales and fins daily. Record chips, cloudiness and red spots, and treat through water quality

Other care

Rinse filter media in tank water. Replacing it all kills filter bacteria and crashes water quality

Protection from predators

• Use a locking lid so cats and children cannot open it
• Watch out for gar teeth when putting hands in the tank. Do not touch fish bare-handed
• Retrieve a jumped-out fish immediately so other pets do not eat it

Foreign-body ingestion

Small items and loose parts in the tank get swallowed. Do not leave stones or broken heater-guard pieces. Swollen belly and refusal to eat: see the vet

Being stepped on

Do not step on a jumped-out fish in the dark. If on the floor, return it to the tank with wet hands. Do not climb on an acrylic tank

Getting pinched

Fins or snout can be pinched when closing the lid. Check the fish is not at the surface before closing. Tidy cables so they do not injure the body

Falls

Jumping out of the tank is the biggest accident. Full lid with weight. When moving, double-bag with little water and do not drop

Escape

Letting loose or releasing is illegal (gar: Invasive Alien Species Act). If you can no longer keep it, consult the shop or a rescue facility; never release into a river

Safe release procedure

1. Stay still and wait for the fish to let go on its own. Do this in the water
2. If it does not let go, turn off the tank lights to calm it
3. Gently push the corner of the mouth open with a wet hand
4. Rinse the wound under running water; leave the fish in the tank

After the release

Rinse and disinfect the wound. See a doctor for deep wounds, swelling or fever. Feed gar commercial food with tweezers

What to tell the vet & what to bring

Water temperature, pH and nitrite readings, tank size and water-change frequency, diet, photos and video of symptoms. Registration card

Checking consciousness, breathing & heartbeat

• Check breathing by gill-cover movement. Normal is 60–80 per minute
• Does it react and move away when touched? Lying on its side is critical
• Eye movement and body color. Cloudy white or blackening are danger signs

Stopping bleeding

• Stop bleeding in fish underwater. Do not take it out of the water
• Do not touch the bleeding area; keep water quality at its best to prevent infection
• Bleeding from the mouth or gills may mean internal injury; see the vet immediately

Transport

• Thick bag with 1/3 water, filled with oxygen, double-bagged
• Place in a polystyrene box, keep at 26–30°C, and carry in the dark and quiet