Cultivating Multi-Trophic Aquaponics: Evaluating Freshwater Shrimp as Biological Detritivores to Reduce Ammonia and Increase Farm Profitability

Commodities

• Animals: fish, shellfish

Practices

• Animal Production: aquaculture
• Education and Training: farmer to farmer
• Production Systems: aquaponics

Small-scale aquaponic operations across the Northeast face a common and costly challenge: solid fish waste accumulates in recirculating tanks, generating ammonia spikes that damage crops, stress fish, and require intensive water exchange or mechanical filtration to manage. This project tests a biological solution with a dual economic benefit - integrating freshwater prawn (Macrobrachium rosenbergii) into the benthic layer of tilapia aquaponic tanks to consume solid waste, reduce ammonia accumulation, and simultaneously produce a premium secondary cash crop.

Conducted across six 300-gallon aquaponic tanks housed in climate-controlled reefer nodes at AI Sustainable Foods' Saylorsburg, PA facility and a commercial partner farm, this 15-month study compares three Control tanks (tilapia only) against three Variable tanks (tilapia plus benthic shrimp) across two full production cycles. Weekly water chemistry measurements - ammonia, nitrite, nitrate, pH, dissolved oxygen, and total suspended solids - will quantify the shrimp's detritivorous impact. Harvest data will generate a comparative enterprise budget documenting the net profitability of multi-trophic versus single-species production.

Outreach is central to this design. Two on-farm Field Days will bring regional CEA producers to view the dual-harvest system and engage with the water chemistry data. A freely distributed 'Freshwater Prawn Integration Guide' will provide setup instructions, enterprise economics, and replication protocols. Results will be presented at the PASA Farming Conference and archived in the Northeast SARE project database.

This project advances SARE's legislative priorities by conserving water, reducing nitrogen loads in effluent discharge, improving agricultural profitability, and expanding employment opportunities in food systems. It addresses a documented operational barrier facing a growing sector of Northeast agriculture with a practical, low-infrastructure, biologically grounded solution.

1. Water Quality: Determine whether the
   introduction of benthic Macrobrachium rosenbergii at a stocking
   density of [X] juveniles per 300-gallon tank reduces total
   suspended solids (TSS) by at least 20% and ammonia spike frequency
   (events exceeding 0.5 mg/L NH3) by at least 20% compared to
   tilapia-only Control tanks, as measured by weekly sensor logging
   and quarterly confirmatory lab analysis over two 6-month production
   cycles.
2. Enterprise Economics: Calculate the net
   revenue-per-square-foot differential between Variable
   (multi-trophic) and Control (single-species) tanks across two
   production cycles, targeting a 15% or greater increase in total
   revenue per unit water volume via the secondary shrimp harvest, and
   document all input costs required to achieve that outcome in an
   enterprise budget replicable by other Northeast operators.
3. Knowledge Transfer: Train a minimum of 40
   regional CEA farmers through two on-farm Field Days; distribute the
   Freshwater Prawn Integration Guide to all attendees and publicly
   via the PASA network and Northeast SARE database; and document
   adoption intent via post-event surveys, with a follow-up survey at
   6 months post-distribution to track actual adoption.