GYMNOTHORAX POLYURANODON FRESHWATER TIGER MORAY EEL LARGE

Freshwater Tiger Moray Eel (Gymnothorax polyuranodon) Care Guide

Overview

• Common Names: Freshwater Tiger Moray Eel, Tiger Moray, Freshwater Moray

• Scientific Name: Gymnothorax polyuranodon

• Origin: Indo-Pacific regions including Papua New Guinea, Indonesia, and Northern Australia

• Maximum Size: 36 inches (90 cm), though most remain around 24 inches in aquaria

• Lifespan: 10–20 years with proper care

• Temperament: Semi-aggressive, predatory

• Tank Level: Benthic (bottom-dweller), hides in crevices and caves

Natural Habitat

Despite the “freshwater” label, G. polyuranodon is naturally found in brackish estuaries, coastal rivers, and occasionally freshwater streams. Juveniles are more tolerant of freshwater, while adults may benefit from light brackish conditions. They inhabit muddy or rocky substrates with plenty of hiding spots.

Aquarium Requirements

Tank Size

• Minimum: 75 gallons for juveniles

• Recommended: 125+ gallons for adults due to their large size and activity

• Shape: Long tanks are preferred to allow swimming room

Water Parameters

• Temperature: 75–82°F (24–28°C)

• pH: 7.0–8.5

• Hardness: 8–20 dGH

• Salinity:

  • Juveniles: Can thrive in full freshwater

  • Adults: Light brackish (SG 1.002–1.005) may improve health and longevity

• Filtration: Powerful canister or sump filter with strong biological filtration—morays are messy eaters

• Oxygenation: Moderate to high; use air stones or surface agitation

Substrate & Décor

• Substrate: Sand or smooth gravel to prevent skin abrasions

• Décor:

  • PVC pipes, large rocks, and driftwood to mimic natural crevices

  • Provide multiple caves to reduce stress

  • Lid is mandatory—these eels are notorious escape artists

Diet & Feeding

Diet Type: Carnivorous

In the wild, they feed on crustaceans, small fish, and mollusks.

Foods to Offer:

• Fresh/frozen shrimp

• Silversides

• Squid

• Tilapia or other white fish

• Earthworms

• Occasionally: live ghost shrimp or feeder guppies (only quarantined, disease-free)

Feeding Tips:

• Feed using tongs to avoid bites

• Offer food every 2–3 days for adults

• Juveniles may require feeding every other day

• Eels often go on "hunger strikes" when stressed—this can last days or even weeks but is usually temporary

Behavior & Tank Mates

Temperament:

• Solitary and territorial

• Generally shy but can be aggressive toward small or slow fish

• Becomes bolder with time

Tank Mates:

• Compatible: Large, fast-swimming fish like Silver Dollars, Monos, Scats (if brackish), or large cichlids

• Avoid: Small fish, invertebrates, bottom dwellers like loaches or catfish (may be eaten)

Health & Longevity

Common Issues:

• Skin infections: From poor water quality or rough substrate

• Parasites: Quarantine new arrivals; morays are prone to internal parasites

• Anorexia: Common under stress or in poor conditions

• Stress-induced hiding: Normal, but prolonged hiding with labored breathing may indicate issues

Maintenance Tips:

• Perform 25–30% water changes weekly

• Monitor ammonia and nitrate levels closely

• Secure the tank lid tightly

Handling & Personality

• Handling: Avoid touching—morays can bite and have sharp teeth

• Intelligence: Can recognize feeders and exhibit curiosity

• Enrichment: Rearranging decor occasionally can stimulate natural behaviors

Breeding in Captivity

There are no confirmed reports of G. polyuranodon breeding in home aquaria. Like many morays, they likely require complex hormonal cues or open ocean conditions to spawn. Their lifecycle may involve a planktonic larval stage, making captive breeding nearly impossible at this time.

Final Thoughts

Gymnothorax polyuranodon is a striking and fascinating species that demands respect from aquarists. While labeled as “freshwater,” it does best in lightly brackish conditions as it matures. With a commitment to water quality, proper feeding, and ample space, this eel can be a show-stopping centerpiece in the right setup.