Japanese eel
Anguilla japonica
Also known asUnagi
Water parameters
Minimum tank: 500 L per individual at harvest size.
Feed and growth
- Feed protein
- 45% target
- Daily feed (warm)
- 1.50% of body weight
- Daily feed (cool)
- 0.50% of body weight
- Max density
- 40 g per litre
A 500 g adult eats about 7.5 g of feed per day at optimum. 10 fish at adult size: ~75 g daily.
Legality
Rules vary by jurisdiction and change over time. Verify with your local fisheries or wildlife authority before stocking.
| Jurisdiction | Status | Notes |
|---|---|---|
| jp | permit required | Glass eel fishing licenses and aquaculture permits required; catch quotas tightening annually verified 2026-05-14 |
| us-general | check local regulations | Not established in US waters; import of live eels is regulated by USFWS verified 2026-05-14 |
Unlisted jurisdictions default to "check local regulations".
Origin and habitat
Native to freshwater rivers, lakes, and coastal waters across East Asia: Japan, Korea, China, Taiwan, and Vietnam. The species (Anguilla japonica) has a catadromous life cycle similar to the European eel: adults migrate to the western Pacific (near the Mariana Trench) to spawn, and larvae drift back on ocean currents to East Asian coasts, arriving as glass eels that migrate upstream. Japanese eel is one of the most culturally important food fish in Japan, where grilled eel (unagi) is a traditional summer dish and a significant culinary tradition. Wild populations have declined severely (listed as Endangered by the IUCN) due to overfishing, habitat loss, and changing ocean conditions. Japanese eel aquaculture is a major industry (over 60,000 tonnes annually, primarily in Japan, China, Korea, and Taiwan) but relies entirely on wild-caught glass eels because captive breeding at commercial scale has not been achieved.
Climate and outdoor ponds
- Climate
- temperate (handles seasonal swings)
- USDA zones
- 6–11 (winter low around -23°C or warmer)
- Heating needed
- yes
- Cooling needed
- no
Care notes
A high-value aquaculture species grown primarily in East Asia for the premium unagi market. Glass eels are wild-caught during the annual upstream migration (primarily November-April), raised in indoor heated ponds or RAS at 25–30°C, and grown to market size (200–300 g) in 12-18 months. FCR on eel pellet (45-50% protein) is 1.5-2.0. Stocking density in intensive Japanese eel farms: 30-80 g/L. The same conservation concerns apply as for European eel: every glass eel used in culture is removed from an endangered wild population. Glass eel prices are extraordinarily high ($10,000-30,000/kg of glass eels in some years), reflecting both scarcity and the premium value of the final product. Japanese unagi retails for $30-80/kg depending on quality and market. For aquaponics, Japanese eel is theoretically compatible but practically restricted by glass eel cost, conservation concerns, and the specialized expertise required for eel culture. Not recommended for home aquaponics operations. Relevant only to commercial-scale East Asian eel farms exploring waste-stream integration with plant production.