Giant freshwater prawn

Quick facts

Adult size

30 cm, 150 g typical harvest weight

Days to harvest

180 to 270 days from fingerling

Lifespan (max)

up to 3 years

Diet

omnivore

Temperature class

warm-water

Difficulty

advanced

Water parameters

Temperature range

22–32°C (optimum 28°C)

pH

7 to 8.5

Hardness

8 to 25 dGH

Minimum tank

300 L per individual at harvest size

Feed and growth

Feed protein

35% target

Daily feed (warm water)

2.50% of body weight per day

Daily feed (cool water)

0.80% of body weight per day

Max stocking density

15 g per litre of system water

A 150g adult eats about 3.8 g of feed per day at optimum temperature. For a roster of 10 fish at adult size, that's around 38 g of feed daily.

Legality

Aquaculture and possession rules vary by jurisdiction and change over time. This table reflects regulations as of the verified date on each row. Verify with your local fisheries or wildlife authority before stocking.

Jurisdictions not listed here default to "check local regulations". A non-listing is not a green light; rules in your specific county or municipality may apply.

Habitat and origin

The giant freshwater prawn (Macrobrachium rosenbergii) is native to rivers and estuaries across Southeast Asia, from India through Malaysia, Thailand, and Indonesia to northern Australia. Larvae develop in brackish water (12-15 ppt salinity); juveniles and adults live in freshwater. The species reaches 25–30 cm body length and 200–500 g in culture, making it the largest commonly farmed freshwater crustacean. It's the basis of a significant aquaculture industry across tropical Asia, with major production in Thailand, India, Bangladesh, China, and Vietnam. Unlike marine shrimp (Penaeus spp.), freshwater prawns can be grown entirely in freshwater systems after the larval stage, making them compatible with aquaponics. The flesh is firm and sweet, comparable to marine prawns, and commands good prices in Asian and specialty Western markets.

Climate and outdoor ponds

Climate classification

tropical (needs warm water year-round)

Outdoor pond zones (USDA)

10 to 13 (winter low around -1°C or warmer)

Heating in a temperate climate

Required for year-round operation

Cooling in a temperate climate

Not required

Zone bounds reflect year-round outdoor pond viability with no active heating. Anywhere outside the bounded zone, the species can still be kept in an indoor heated tank or a seasonally-managed system. Verify your specific microclimate, as a sheltered yard zone can run a half-zone warmer than the regional rating.

Care notes

An advanced aquaponics addition that provides both nutrient input (prawn waste feeds plants) and a high-value harvest product. Prawns are grown at 26–32°C in the same water as fish; tilapia + prawn polyculture is a well-established practice in Asian aquaculture. They're bottom-dwellers that eat detritus, uneaten fish feed, and supplemental prawn pellet (30-35% protein). Growth to market size (50–100 g) takes 6-9 months from post-larval stage. The main management challenge is that prawns are territorial and cannibalistic, especially during molting when the soft-shelled individual is vulnerable. Dense substrate structure in the tank (bundles of nylon mesh, sections of PVC pipe, or netting hung vertically) provides hiding spots during molting and reduces aggression losses. Stocking density is calculated by bottom area, not volume: 5-15 prawns per square meter of tank bottom. The larvae require brackish water for 30-45 days of development through about 11 larval stages before they metamorphose into post-larvae that can survive in freshwater. This means you either need a separate brackish larval rearing setup or you buy post-larvae (PLs) from a hatchery. Most home aquaponics keepers buy juvenile prawns. Legal status is generally permissive; M. rosenbergii is approved for aquaculture in most US states. Market value is high ($15-30/kg), so even a small harvest from a polyculture system provides meaningful return.

Further reading

• Aquaponics water chemistry: balancing pH for fish and plants
• Fish for aquaponics: tilapia vs everything else