Why We No Longer Count Stocking Density Reductions Towards Our Impact

FWI has been operating the Alliance for Responsible Aquaculture (ARA) in Andhra Pradesh, India, for almost five years. In this alliance, farmers commit to maintaining water quality and stocking density within our welfare limits. 

Until now, the almost 5 million fishes we counted as helped through the ARA came from two sources: improvements in water quality and stocking density reductions of more than 20% into our acceptable range.

We have now decided to stop counting fishes from stocking density reductions as helped. We are making this change because the evidence for stocking density as a welfare improvement in our context remains shallow, and because these cases made up only a very small share of our overall impact. Given that uncertainty, we think the more conservative and transparent approach is to stop treating these reductions as direct impact.

Why We Are No Longer Counting These Reductions Towards Our Impact

Our Monitoring & Evaluation review of the ARA highlighted two key issues with our stocking density limits:

1.) The evidence base is shallow in our context

The evidence that lower stocking densities improve the welfare of Indian major carp in ponds is limited. There are some relevant papers (e.g., this and this), but they are from different farming systems. We could conduct our own study, but it is difficult to cleanly isolate stocking density as the key driver of better welfare in dynamic pond environments. In other words, we still think lower stocking densities may help, but we are no longer confident enough to count that relationship as direct impact.

2.) These cases make up only a very small share of our impact

Because of this uncertainty, we had already set a high bar for counting stocking density reductions. We counted reductions only when we could verify them with harvest data and when they were at least 20%. Due to this conservative approach, stocking density reductions accounted for less than 1% of our impact in 2024 and 2025.

Why We Still Retain Stocking Density Limits

Although we are no longer counting stocking density reductions as impact, we are keeping stocking density limits in the ARA for two reasons:

• Preventing increases in stocking density: Early in the program, some farmers told us that better water quality could allow them to stock more fishes. For rural farmers, poor water quality can be one of the main constraints on how many fishes they keep. Because of that, we did not want a program centered on improving water quality to unintentionally lead to higher stocking densities. Including a stocking density limit helps us guard against that.

  
  

• Improving welfare: Lower stocking densities may still benefit welfare. Presumably, fewer fishes in a pond means more space per individual and likely less pressure on water quality, because fewer fishes produce waste and consume oxygen. However, we no longer think the evidence is strong enough for us to count these reductions as direct impact in our current monitoring.

What This Means in Practice

This change does not alter how the ARA operates. Our staff still requires farmers to stay within our stocking density limits, and we will continue monitoring compliance. Farmers who do not adhere to these limits are removed from the alliance. 

Because stocking density reductions made up such a small part of our impact numbers, we do not expect this change to meaningfully affect our cost-effectiveness or total fishes helped. We want our impact reporting to reflect the outcomes we can support with enough confidence, and stocking density reductions no longer fit that description.

One of our ARA farmers in front of his farm in Andhra Pradesh, India. This is one of the farms where we helped fishes through water quality improvements in November 2025.